- cafer
- caglei
- Callagur
- callirostris
- callosites
- callosity
- calvata
- cantorii
- capaxorder
- capolongoi
- carajasensis
- carapace
- carbonaria
- Caretta
- carinatus
- carnivorous
- carolina
- caroticum foramen
- carotid canal
- carpals
- carpus
- cartilage
- cartilaginea
- caruncle
- caspica
- castaneus
- cataspila
- caudal
- cavernosum canal
- cavity scala tympani
- cellulose
- centrata
- centromere
- cephalic
- cervical extensor muscles
- cervical scute
- cervical vertebrae
- chacoensis
- chapalaense
- chapini
- chathamensis
- Chelodina
- Chelydra
- Chersina
- chichiriviche
- chilensis
- chimalhuaca
- Chinemys
- Chitra
- choanae
- chorion
- chriskarannarum
- chromosome
- chrysea
- Chrysemys
- circumdata
- CITES
- clade
- cladogram
- Claudius
- clavicle
- cleithrum
- clines
- cloaca
- cloacal bursae
- coahuila
- coelomic cavity
- coitus
- colchica
- concave
- concinna
- condylobasal
- congener
- Congo-Brazzaville
- conical
- conspecific
- convergence
- convex
- copulation
- copulatory organ
- coriacea
- coronata
- coronoid bones
- corpora albicantia
- corpus albicans
- corpus luteum
- cortical canal
- costal bones
- costiform process
- couro
- cranium
- crassicollis
- creaseri
- crepuscular
- Critically endangered
- cruciform
- cruentatum
- crus crura
- crustacea
- cultiform
- Cuora
- cusp
- cutaneous
- Cyclanorbis
- Cyclemys
- Cycloderma