- Cactus coral
- cactus, Pavona
- Caddisfly
- Cadella, genus
- Cadella lubrica
- caelatus, Nassarius
- caespitosum, Cystophyllum
- Calamagrostis, genus
- Calappa lophos
- calcarea, Macoma
- calcarea izurensis, Macoma
- Calf cowry
- californianus lobatus, Zalophus
- californiense, Clinocardium
- californiense, Keenocardium
- calipygos, Anodonta
- calipygos, Sinanodonta
- Callianassa, genus
- Callianassa nishikawai
- Callianassa shikamai
- Callianassa titaensis
- Callianopsis titaensis
- Calliostoma, genus
- Calliostoma (Calotropis) haliarchus
- Calliostoma (Calotropis) hataii
- Calliostoma consors
- Calliostoma haliarchus
- Calliostoma hataii
- Calliostoma otaniensis
- Calliostoma (Tristichotrochus) consors
- Callispira, genus
- Callista, genus
- Callista matsuraensis
- Callista brevisiphonata
- Callithaca adamsi
- callosa japonica, Vicarya
- Calocedrus notoensis
- Calocycletta costata
- Calopodium, genus
- Calopodium (Kennerlia), genus
- Calosoma, genus
- Calosoma maximowiczi
- Calyptogena, genus
- Calyptogena chitanii
- Calyptogena kawamurai
- Calyptogena nipponica
- Calyptogena pacifica
- Calyptraea, genus
- Calyptraea hataii
- Calyptraea tubura
- Camarophoria, genus
- Camellia, genus
- Camellia protojaponica
- Camerina bagualensis
- campanulatus, Enkianthus
- camphora, Cinnamomum
- Camphor laurel
- Camphor tree
- Camphorwood
- Camponotus, genus
- Campopleginae, subfamily
- Camptandrium, genus
- Camptopteris japonica
- Canadoceras, genus
- Canadoceras kossmati
- Canarium (Doxander) japonicum
- Canarium japonicum
- Canavaria, genus
- Cancellaria, genus
- Cancellaria (Habesolatia) nodulifera
- Cancellaria kobayashii
- Cancellaria mutsuana
- Cancellaria nodulifera
- Cancellaria spengleriana
- Cancellaria (Sydaphera) spengleriana
- cancellata, Cyclammina
- Cancellina, genus
- Cancellina nipponica
- Cancer minutoserratus
- Cancer sambonsugii
- candelabrum, Boreotrophon
- candelabrum, Trophon
- candelabrum, Trophonopsis
- candida, Turbonilla
- Canis, genus
- Canis lupus
- Canis lupus subsp. hodophilax
- Cantao yamanai
- capillacea, Meropesta
- capitata f. capitata, Synedra
- capitata, Synedra
- capitata, Synedra capitata
- Capitulum, genus
- Capnuchosphaera, genus
- Capricornis, genus
- Caprifoliaceae, family
- Caprina uwajimensis
- capsoides, Merisca
- capsoides, Serratina
- Carabidae, family
- Carabus, genus
- Carassius, genus
- Carbonoschwagerina minatoi
- Carbonoschwagerina morikawai
- Carcharhinus, genus
- Carcharhinus acanthodon
- Carcharhinus brevipinna
- Carcharhinus priscus
- Carcharias, genus
- carcharias, Carcharodon
- Carcharias obliquus
- Carcharias taurus
- Carcharocles megalodon
- Carcharodon, genus
- Carcharodon angustidens
- Carcharodon carcharias
- Carcharodon hastalis
- Carcharodon megalodon
- Carcinophyllum, genus
- Carcinoplax, genus
- Carcinoplax antiqua
- carconensis, Stephanodiscus
- Cardiandra alternifolia
- Cardilia toyamaensis
- Cardilia yudaensis
- Cardinia, genus
- Cardinia toriyamai
- Cardiomya gouldiana
- Cardiomya mitsuganoensis
- Cardita, genus
- Cardita minoensis
- Carditella hanzawai
- Carditellopsis toneana
- Cardium, genus
- Cardium hizenense
- Cardium shiobarense
- Carduoideae, subfamily
- Carex, genus
- Carex rhynchophysa
- Carex utriculata
- carinata, Arctostrea
- carinata, Tetorimya
- carinatum, Rastellum
- carinatus, Unionites
- carmanahensis, Securella
- Carpenter ant
- carpinoides, Carpinus
- carpinoides, Ulmus
- Carpinus, genus
- Carpinus carpinoides
- Carpinus cordata
- Carpinus erosa
- Carpinus heigunensis
- Carpinus japonica
- Carpinus laxiflora
- Carpinus miocenica
- Carpinus mioturczaninovii
- Carpinus subcordata
- Carpinus subyedoensis
- Carpinus tschonoskii
- carpio, Cyprinus
- Carpolithes japonica
- carrerei, Neocalamites
- Cartilaginous fish
- Cartorhium coristum
- Carya, genus
- Carya cathayensis
- Carya miocathayensis
- Carya ovatocarpa
- Carya sinensis
- Caryophyllaceae, family
- Caryophyllia, genus
- Caryophyllia compressa
- Caryophyllia (Premocyathus) compressa
- Cassidulina globosa
- Cassidulina japonica
- Cassidulina kasiwazakiensis
- Cassidulina pacifica
- Cassidulina subglobosa
- Cassidulina sublimbata
- Cassidulina yabei
- Cassidulita kasiwazakiensis
- cassinaeformis, Venus
- cassis, Fabiania
- casta, Leucotina
- Castanea, genus
- Castanea crenata
- Castanea miomollissima
- Castanopsis, genus
- Castanopsis miocuspidata
- Castanopsis sieboldii
- castellata, Anadara satowi
- castellata, Scapharca
- castus, Nassarius
- Casuarinaceae, family
- Cat
- Cataoceramus balticus
- cathayensis, Carya
- Cathaysiopteris, genus
- Cathaysiopteris whitei
- Cat's paw coral
- Caudites posterocostatus
- Caulastraea tumida
- Cavilucina kitamurai
- Cavolinia raritatis
- Cavolinia tridentata
- Cecidomyiidae, family
- Cedrela nipponica
- Celastrus orbiculatus
- Cellana, genus
- Celtis, genus
- Celtis jessoensis
- Cephalopod
- Cephalopoda, class
- Cephalotaxus, genus
- Cephalotaxus obounta
- Cerambycidae, familly
- Cerasus, subgenus
- Cerasus maximowiczii
- Cerasus sargentii
- Ceratocyrtis, genus
- Ceratocyrtis sinuosa
- Ceratoikiscum, genus
- Ceratophyllum, genus
- Ceratophyllum demersum
- Ceratostoma aduncum
- Ceratostoma inornatum
- Ceratostoma japonica
- Ceratostoma (Ocinebra) aduncum
- Cercidiphyllum, genus
- Cercidiphyllum crenatum
- Cercidiphyllum japonicum
- Cercidiphyllum magnificum
- Cercis, genus
- Cercomya gurgitis
- Cerithidea, genus
- Cerithidea (Cerithideopsilla) yatsuoensis
- Cerithidea djadjariensis
- Cerithidea tokunagai
- Cerithidea yatsuoensis
- Cerithideopsilla, genus
- Cerithideopsilla cingulata
- Cerithideopsilla djadjariensis
- Cerithideopsilla yatsuoensis
- Cerithidium fusca
- Cerithidium fuscum
- Cerithium coralium
- Cerithium eminulum
- Cerithium ishiiana
- Cerithium kaneharai
- Cernina nakamurai
- Cervidae, family
- Cervus, genus
- Cervus (Axis) japonicus
- Cervus (Deperetia) shimabarensis
- Cervus grayi subsp. katokiyomasai
- Cervus japonicus
- Cervus kazusensis
- Cervus kyushuensis
- Cervus natsumei
- Cervus nippon
- Cervus (Nipponicervus) kazusensis
- Cervus (Nipponicervus) praenipponicus
- Cervus nippon subsp. yesoensis
- Cervus paleoezoensis
- Cervus praenipponicus
- Cervus (Rusa) kyushuensis
- Cervus shimabarensis
- Cervus (Sika) natsumei
- Cetacea, infraorder
- Cetartiodactyla, order
- Cetotheriidae, family
- Chaenomeles japonica
- Chaetetes, genus
- Chaetetes nagaiwaensis
- Chaetetopsis crinita
- Chaetoceros, genus
- Chalaroschwagerina vulgaris
- chalcidicum tanabensis, Cyphastrea
- Chalice bubble snail
- Chalice coral
- Chalky macoma
- Chamaecyparis, genus
- Chamaecyparis pisifera
- Chamidae, family
- chaneyi, Cladrastis
- chaneyi, Mucuna
- chaneyi, Osmanthus
- , Aokiichthys
- Charonia, genus
- Charonia lampas
- Charybdis (Charybdis) japonica
- Charybdis japonica
- Chauliodontidae, family
- Chauliodontinae, subfamily
- Chavania striata
- chehalisensis, Portlandia
- Cheirurus (Crotalocephalus) japonicus
- Cheirurus japonicus
- Chelonia, genus
- Cheloniceras, genus
- Cheloniceras meyendorffi
- Chelonioidea, superfamily
- Chelyconus, genus
- Chengiopanax sciadophylloides
- Cherry blossom
- chichibuensis, Anadara
- chichibuensis elegantula, Turritella
- chichibuensis, Mizuhopecten
- chichibuensis, Patinopecten
- chichibuensis, Terebratulina
- chichibuensis, Turritella
- chichibu, Scomberomorus
- Chicoreus asanoi
- Chicoreus asianus
- Chicoreus palmarosae
- Chicoreus (Rhizophorimurex) asanoi
- Chicoreus (Rhizophorimurex) tiganouranus
- Chicoreus tiganouranus
- chigayensis, Thracia
- chikuzenensis, Echinodiscus
- chikuzenensis, Dosinia
- chikuzenensis, Phacosoma
- Chilotherium pugnator
- Chimaera, genus
- Chinaberry
- chinensis, Anomia
- chinensis, Mactra
- chinensis, Prionailurus bengalensis
- chinensis ssp. rhynchophylla, Fraxinus
- Chinese cork oak
- Chinese hat snail
- Chinese hickory
- Chinese jingle shell
- Chinese leopard cat
- Chinese pond mussel
- Chinese striped-necked turtle
- Chinese swamp cypress
- Chinese sweet gum
- Chinese tallow
- chino var. chino, Pleioblastus
- chino, Pleioblastus
- chino, Pleioblastus chino
- Chinquapin
- Chione (Gnidiella) richthofeni
- Chione (Gnidiella) trigona
- Chione richthofeni
- Chione tateiwai
- Chione trigona
- Chionopsis richthofeni
- Chionopsis trigona
- Chironomid
- Chironomidae, family
- chitaniana, Mercenaria
- chitaniana, Plesioacirsa
- chitaniana, Securella
- chitanii, Adulomya
- chitanii, Akebiconcha
- chitanii, Calyptogena
- chitanii, Makiyama
- Chiton
- Chlamys, genus
- Chlamys akahirensis
- Chlamys akitana
- Chlamys akutsui
- Chlamys albida
- Chlamys arakawai
- Chlamys ashiyaensis
- Chlamys asperulata
- Chlamys cosibensis
- Chlamys cosibensis heteroglypta
- Chlamys crassivenia
- Chlamys crassivenium
- Chlamys daishakaensis
- Chlamys (Decatopecten) izuensis
- Chlamys farreri
- Chlamys farreri nipponensis
- Chlamys hataii
- Chlamys imanishii
- Chlamys inouei
- Chlamys irregularis
- Chlamys ishidae
- Chlamys islandica
- Chlamys islandica erythrocomata
- Chlamys itoigawae
- Chlamys iwakiana
- Chlamys iwamurensis
- Chlamys izuensis
- Chlamys jousseaumei
- Chlamys kakisakiensis
- Chlamys kaneharai
- Chlamys (Leochlamys) tanassevitschi
- Chlamys (Mimachlamys)‘®
- Chlamys (Mimachlamys) kaneharai
- Chlamys (Mimachlamys) satoi
- Chlamys miurensis
- Chlamys miyatokoensis
- Chlamys mojsisovicsi
- Chlamys nipponensis
- Chlamys nisataiensis
- Chlamys otukae
- Chlamys satoi
- Chlamys squamata
- Chlamys swiftii
- Chlamys swiftii var. etchegoini
- Chlamys (Swiftopecten) swiftii
- Chlamys tanassevitschi
- Chlamys vesiculosus
- Chlamys yagurai
- Chlorophyta, phylum
- Chlorostoma, genus
- Chlorostoma hiranitensis
- Chlorostoma microstriata
- Choerospondias axillaris var. polymeris
- Choffatia, genus
- Chondrichthyes, class
- Chonetes, genus
- Choristodera, order
- Chrysanthemum, genus
- chrysanthemum, Cleviceras
- Chrysanthemum makinoi
- Chrysomelidae, family
- Chuhsiungichthys japonicus
- Chuhsiungichthys yanagidai
- Chusenella, genus
- Chusenella crassa
- Cibicides, genus
- Cibicides datensis
- Cibicides lobatulus
- Cibicides refulgens
- Cibicides pseudoungerianus
- Cibicidoides lobatulus
- Cibicidoides pseudoungeriana
- Cibicidoides wuellerstorfi
- Cicada
- Cicadoidea, superfamily
- Cichorioideae, subfamily
- Cidaris, genus
- Ciliatocardium ciliatum
- ciliatum, Ciliatocardium
- ciliatum, Clinocardium
- Cimbex connatus taukushi
- Cimbicidae, family
- Cinctiscala sagamiensis
- Cinctiscala sagamiensis azumana
- cinerea, Juglans
- cinerea var. megacinerea, Juglans
- cingulata, Cerithideopsilla
- cingulata, Pirenella
- cingulifera, Turritella
- Cinguloterebra fenestrata
- Cinnamomum, genus
- Cinnamomum camphora
- Cinnamomum daphnoides
- Cinnamomum lanceolatum
- Cinnamomum miocenum
- Cinnamomum tenuifolium
- Cinnamomum yabunikkei
- cipangoana, Megacardita
- cipangoana, Venericardia
- cipangoana, Venericardia kiiensis
- Cipangopaludina japonica
- Circe, genus
- circularis, Miliolinella
- circularis, Praeorbulina
- circularis, Praeorbulina glomerosa
- circumpicta, Ostrea
- Cirolanidae, family
- cisshuensis, Glycymeris
- Citrus flower chafer
- Cladophlebis, genus
- Cladophlebis acutipennis
- Cladophlebis denticulata
- Cladophlebis distans
- Cladophlebis exiliformis
- Cladophlebis geyleriana
- Cladophlebis haiburnensis
- Cladophlebis kuzuryuensis
- Cladophlebis nebbensis
- Cladophlebis nihei-takagii
- Cladophlebis raciborskii
- Cladrastis, genus
- Cladrastis aniensis
- Cladrastis chaneyi
- Cladrastis platycarpa
- Clam shrimp
- Claspingleaf pondweed
- Clathrodrillia flavidula
- Clathrodrillia takeokensis
- Clathrofenella reticulata
- Clathropteris, genus
- Clathropteris meniscoides
- Clathrus, genus
- clausa, Cryptonatica
- clausa tugaruana, Natica
- Clausiliidae, family
- clavigera, Reishia
- Cleiothyridina hayasakai
- Clematis apiifolia
- Clematis apiifolia var. biternata
- Clementia, genus
- Clementia nakamurai
- Clementia papyracea
- Clementia vatheliti
- Clemmys, genus
- Cleoniceras, genus
- Clerodendrum, genus
- Clethra barbinervis
- Clethrionomys rufocanus
- Cleviceras chrysanthemum
- Click beetle
- Climbing hydrangea
- Clinocardium, genus
- Clinocardium andoi
- Clinocardium asagaiensis
- Clinocardium braunsi
- Clinocardium californiense
- Clinocardium ciliatum
- Clinocardium decoratum
- Clinocardium fastosum
- Clinocardium (Fuscocardium) braunsi
- Clinocardium (Keenocardium) californiense
- Clinocardium nuttallii
- Clinocardium ohganense
- Clinocardium okushirense
- Clinocardium pseudofastosum
- Clinocardium shinjiense
- Clinocardium shinjiensis
- Clinocardium shiobarense
- Clinopegma, genus
- Clio, genus
- Clio balantium
- Clio recurva
- Clisaxophyllum, genus
- Clisiophyllum ehimense
- Clisiophyllum subramosum
- Clithon oualaniense
- Clithon oualaniensis
- Clothed bittersweet
- Clove cherry
- Club-rush
- Club spikemoss
- Clupeidae, family
- Coast redwood
- coaxans, Geloina
- Cocconeis, genus
- Cocconeis contrerasi
- Cocconeis costata
- Cocconeis diminuta
- Cocconeis neodiminuta
- Cocconeis placentula
- Cocconeis placentula var. euglypta
- Cocconeis thumensis
- Cocconeis vitrea
- Cocconema parvum
- Cocculina japonica
- cochlea, Heteropsammia
- Cockroach
- Cockscomb pearl mussel
- Codonellina montferrandii
- Codonofusiella, genus
- Codonofusiella paradoxica
- Coelogasteroceras, genus
- Coelogasteroceras giganteum
- coignetiae, Vitis
- Colania, genus
- colaniae, Neoschwagerina
- Coleoptera, order
- Collembola, order
- Colombiceras satowi
- columbiana, Lucinoma
- Comb pen shell
- Comitas, genus
- commixta, Sorbus
- Common box crab
- Common carp
- Common Geloina
- Common reed
- commune, Nonion
- communis, Phragmites
- compacta subsp. minor, Conchocele
- complanata var. japonica, Operculina
- complanata, Operculina
- Compositae, family
- compressa, Caryophyllia
- compressa, Premocyathus
- Comptonia, genus
- Comptonia japonica
- Comptonia kidoi
- Comptonia naumanni
- Comptoniphyllum, genus
- Comptoniphyllum naumanni
- comta, Cyclotella
- Conasprella sieboldii
- concentricum, Lucinoma
- Conchocele, genus
- Conchocele bisecta
- Conchocele compacta subsp. minor
- Conchocele disjuncta
- Conchocele nipponica
- concinna, Fulgoraria
- concolor, Nicrophorus
- Cone-shaped nassa
- Cone shell
- conflexa, Cypridodella
- confusa kongiensis, Nuculana
- confusa kongiensis, Saccella
- confusa, Nuculana
- confusa, Saccella
- confusa sematensis, Nuculana
- conica, Trachydomia
- conica, Trachyspira
- Conidae, family
- Conifer
- Coniferophyta, phylum
- Coniopteris, genus
- Coniopteris burejensis
- conjunctum, Epitonium
- connatus taukushi, Cimbex
- Conodont
- Conodonta, class
- conoidalis, Nassarius
- Conotalopia, genus
- consors, Calliostoma
- consors, Tristichotrochus
- constricta, Neptunea
- constricta, Sinonovacula
- constricticollis, Plateumaris
- construens, Fragilaria
- construens var. venter, Fragilaria
- contraria, Antiplanes
- contrerasi, Cocconeis
- controversa, Cornus
- controversa, Swida
- Conus, genus
- Conus (Endemoconus) oyamai
- Conus moniwaensis
- Conus oyamai
- Conus sieboldii
- Conus tokunagai
- Conus tuberculatus
- Conus yoshidensis
- convexa, Glycymeris
- Convexastrea, genus
- convexiuscula, Ginebis
- convexiusculus, Bathybembix argenteonitens
- Cooperina inexpectata
- Cooperina nipponica
- Coptothyris grayi
- Coral cerith
- coralium, Cerithium
- Corallina, genus
- Corbicula, genus
- Corbicula astrata
- Corbicula fuscata var. astrata
- Corbicula japonica
- Corbicula (Mesocorbicula) tetoriensis
- Corbicula sanchuensis
- Corbicula sandai
- Corbicula tetoriensis
- Corbula, genus
- Corbula erythrodon
- Corbula venusta
- Corbula yokoyamai
- Cordaites, genus
- Cordaites japonicus
- Cordaites palmaeformis
- cordata, Aralia
- cordata, Carpinus
- cordata, Liquidambar formosana
- Cordia, genus
- cordiformis, Juglans mandshurica
- Cordylidae, family
- coreanica, Searlesia
- coreanica, Terebratalia
- coreanicus, Fusolatirus
- Coreidae, family
- coristum, Cartorhium
- Cork-tree
- cornigera, Yeharaia
- Cornucoquimba kagitoriensis
- Cornucoquimba moniwensis
- Cornucoquimba saitoi
- Cornus, genus
- Cornus controversa
- Cornus kousa
- Cornus miowalteri
- cornutus, Rhinolophus
- coronata correensis, Lunella
- coronata, Triassocampe
- Coronocephalus, genus
- Coronula, genus
- corpulenta, Eoscaphander
- correensis, Lunella
- correensis, Lunella coronata
- correensis, Turbo
- corrugata, Dosinia
- corrugata, Spiroloculina
- coruscus, Mytilus
- Corwenia mizuyagadaniensis
- Corylopsis, genus
- Corylopsis gotoana
- Corylus, genus
- Corylus heterophylla
- Corylus heterophylla var. thunbergii
- Corylus sieboldiana
- Coryphaenoididae, family
- Coryphodon, genus
- Coscinaraea, genus
- Coscinodiscus, genus
- Coscinodiscus excentricus
- Coscinodiscus lacustris
- Coscinodiscus lineatus
- Coscinodiscus marginatus
- Coscinodiscus robustus f. robustus
- Coscinodiscus yabei
- cosibensis, Chlamys
- cosibensis heteroglypta, Chlamys
- Cosmopolitodus, genus
- Cosmopolitodus hastalis
- costata, Betula
- costata, Calocycletta
- costata, Cocconeis
- Costate button top
- costatum, Suchium
- costatum, Umbonium
- costatus, Turrilites
- Costocyrena, genus
- Costocyrena otsukai
- Costocyrena radiatostriata
- coticazae, Glossaulax
- coticazae, Glossaulax didyma
- coticazae
- coticazae, Neverita didyma
- Cottus, genus
- couthouyi, Admete
- cowperi var. yubarensis, Propeamussium
- Cowry
- coxi, Aturia
- Crab
- crabro, Diploneis
- crabro, Pinnularia
- Crab spider
- Cranberry
- Crane
- Craseomys rufocanus
- Craspedosmilia, genus
- crassa, Chusenella
- crassaformis, Globorotalia
- crassa, Glycymeris
- crassa, Pseudofusulina
- Crassatella, genus
- Crassatella (Eucrassatella) nana
- Crassatella (Eucrassatella) yabei
- Crassatella nana
- Crassatella nipponensis
- Crassatella pauxilla
- Crassatella tenuiliratus
- Crassatella yabei
- Crassatellites, genus
- Crassatellites (Eucrassatella) yabei
- Crassatellites nanus
- Crassatellites oblongata
- Crassatellites pauxillus
- Crassatellites tenuiliratus
- Crassatellites yabei
- crassidens, Cyclocardia
- crassicostatus, Hollandites japonicus
- Crassispira takeokensis
- crassitesta, Mytilus
- crassivenia, Chlamys
- crassivenium, Chlamys
- crassivenium, Gloripallium
- crassoradiata, Maedagonia
- crassoradiata, Apiotrigonia
- Crassostrea, genus
- Crassostrea gigas
- Crassostrea gravitesta
- Crassostrea nippona
- crataegifolium, Acer
- crataegifolius, Rubus
- Crataegus maximowiczii
- craticulifera, Neoschwagerina
- crebricostata, Cyclocardia
- crenata, Aspalima
- crenata, Astarte
- crenata, Castanea
- crenata, Deutzia
- crenata, Eucrate
- crenata, Fagus
- crenatum, Cercidiphyllum
- Crenella decussata
- Crenella yokoyamai
- Crenocrassatella foveolata
- Crenomytilus grayanus
- Crenotrapezium, genus
- Crenulilimopsis oblonga
- Crepidula, genus
- Crepidula grandis
- Crepidula isimotoi
- Crepidula jimboana
- Cribroelphidium poeyanum
- Cribrogenerina, genus
- Cricket
- Crimson glory vine
- crinita, Chaetetopsis
- Crinoid
- Crinoid, class
- Crioceras, genus
- crispata, Oulastrea
- crispula, Quercus
- crispula, Quercus mongolica
- crispum, Elphidium
- Cristaria, genus
- Cristaria kuboi
- Cristaria muroii etomoensis
- Cristaria plicata
- Cristaria plicata spatiosa
- Cristaria spatiosa
- cristianensis, Archaeosemantis
- Crocodilia, order
- Crocodylidae, family
- crossei, Mactra
- crossei, Terebratulina
- Cross-sculpture crenella
- Crotalocephalina secta
- Crotalocephalus japonicus
- crucigera, Tellinella
- Cruciloculina triangularis
- crumpii, Ginebis
- crumpii, Lischkeia
- Crump's margarite
- Cryptinae, subfamily
- Cryptobranchidae, family
- cryptolineata, Securella
- Cryptomeria, genus
- Cryptomeria japonica
- Cryptomya busoensis
- Cryptonatica affinis
- Cryptonatica andoi
- Cryptonatica clausa
- Cryptonatica janthostoma
- Cryptonatica janthostomoides
- Cryptonatica russa
- Cryptonatica tugaruana
- Cryptopecten, genus
- Cryptopecten nux subsp. sematensis
- Cryptopecten sematensis
- Cryptopecten vesiculosus
- Cryptopecten yanagawaensis
- Cryptostephanidium, genus
- Cucujoidea, superfamily
- Cucullaea acuticarinata
- Cucullaea ponderosa
- Cudrania tricuspidata
- Cuifastraea, genus
- Culicia japonica
- Culicia stellata
- Culicidae, family
- Cultellus, genus
- Cultellus attenuatus
- Cultellus izumoensis
- Cultellus otukai
- Cultellus rectangulus
- cumingi, Cycladicama
- cumingii, Batillaria
- cumingii, Cycladicama
- cumingii, Joannisiella
- Cummingella, genus
- cuneata, Laevichlamys
- cuneata, Latona
- Cuneate wedge shell
- cuneatus, Donax
- cuneiformis, Hemidiscus
- cuneiformis, Mya
- Cuneopsis, genus
- Cuneopsis gracilenta
- Cuneopsis okuyamai
- Cunninghamia, genus
- Cunninghamia konishii
- Cuora miyatai
- Cupressaceae, family
- Cupressioxylon, genus
- Curculionidae, family
- Curcuma, genus
- curta, Astrea
- curta, Montastrea
- curva, Praeorbulina
- curvata, Rhoicosphenia
- Cuspidaria, genus
- Cuspidaria araii
- Cuspidaria gouldiana septentrionalis
- cuspidata, Taxus
- cuspidatum, Polygonum
- Cyanobacteria, phylum
- Cyathophylum, genus
- Cybister, genus
- Cycad
- Cycadeoid
- Cycadeoidea, genus
- Cycadeoidea buchiana
- Cycadeoidea ezoana
- Cycadocarpidium naitoi
- Cycadocarpidium osawae
- Cycadophyta, phylum
- Cycladicama, genus
- Cycladicama cumingi
- Cycladicama cumingii
- Cycladicama takeyamai
- Cyclammina, genus
- Cyclammina cancellata
- Cyclammina incisa
- Cyclammina japonica
- Cyclammina orbicularis
- Cyclammina pauciloculata
- Cyclammina tani
- Cyclemys akiyoshiensis
- Cyclemys miyatai
- Cyclestherida, order
- Cyclestherioides, genus
- Cyclina, genus
- Cyclina japonica
- Cyclina lunulata
- Cyclina orientalis
- Cyclina sinensis
- Cyclobalanopsis, subgenus
- Cyclobalanopsis inouei
- Cyclobalanopsis nathorstii
- Cyclobalanopsis praegilva
- Cyclocardia, genus
- Cyclocardia akagii
- Cyclocardia crassidens
- Cyclocardia crebricostata
- Cyclocardia elliptica
- Cyclocardia ferruginea
- Cyclocardia isaotakii
- Cyclocardia laxata
- Cyclocardia myogadaniensis
- Cyclocardia ochiaiensis
- Cyclocardia paucicostata
- Cyclocardia siogamensis
- Cyclocardia takedai
- Cyclocardia tokunagai
- Cyclocarya paliurus
- Cyclopecten tochigiensis
- cyclopis, Macaca
- Cyclostigma, genus
- cyclostoma, Globigerina
- cyclostoma, Globigerinoides
- Cyclosunetta, genus
- Cyclotella, genus
- Cyclotella comta
- Cyclotella ocellata
- Cyclotella stylorum
- Cyclus, genus
- Cylichna affabilis
- Cylichna biplicata
- Cylichna kantoensis
- Cylichnatys angusta
- Cylichnidae, family
- Cymatium (Ranularia) subpyrum
- Cymatium subpyrum
- Cymatoceras, genus
- Cymatoceras pseudoneokomiense
- Cymbella, genus
- Cymbella lanceolata
- Cymbella parva
- Cymostrophia, genus
- Cynarina lacrymalis
- Cyperaceae, family
- Cyperus, genus
- Cyphastrea chalcidicum tanabensis
- Cyphastrea japonica
- Cyphastrea microphthalma
- Cyphastrea tanabensis
- Cypraea, genus
- Cypraea itoigawai
- Cypraea vitellus
- Cypraea (Zoila) itoigawai
- Cypress
- Cypridodella conflexa
- Cyprinidae, family
- Cyprinus, genus
- Cyprinus carpio
- Cyrena naumanni
- Cyrena radiatostriata
- Cyrena shiroiensis
- Cyrenidae, family
- cyrenoides, Ennucula
- cyrenoides, Sinonucula
- Cyrtocapsella, genus
- Cyrtocapsa, genus
- Cyrtocapsella japonica
- Cyrtocapsella tetrapera
- Cyrtospirifer verneuili
- Cystammina pauciloculata
- Cystiphyllum, genus
- Cystoid
- Cystoidea, class
- Cystophyllum caespitosum
- Cystophyllum sisymbroides
- cytaeum, Anomia
- Cythere omotenipponica
- Cytheropteron sendaiense