202 REPORT OF NEW JERSEY STATE MUSEUM. 
Order TESTUDINATA. 
The Turtles. 
Body enclosed between 2 more or less developed bony shields 
which are usually covered by horny epidermal plates and some- 
times by a leathery skin. Upper shield or carapace, and lower 
shield or plastron, more or less united along sides. Neck and 
tail only flexible parts of spinal column, and these together with 
legs usually retractile within box made by shields. No teeth, 
edges of jaws encased in horny sheaths usually with sharp cut- 
ting edges. Eye furnished with 2 lids and a nictitating mem- 
brane as in birds. ‘Tympanic membrane always present, though 
sometimes hidden by skin. Respiration effected by swallowing 
air. Bony part of carapace formed by dorsal and sacral verte- 
bree and ribs co-ossified with a series of underlying bony plates, 
usually accompanied by a marginal row. Dorsal vertebrz with 
their ends flattened and immovably united by cartilage, and all 
except first and last with neural spines flattened horizontally so 
as to form median line of plates. On either side of this series 
a single row of ossified dermal plates overlying ribs, and corre- 
sponding in number to developed ribs, of which there are usually 
8 pairs. No true sternum. Plastron consisting of membrane 
bones, usually of g pieces, as 4 pairs and a single symmetrical 
median piece. Osseous plates both above and below correspond 
neither in number or position with overlying dermal plates. 
Quadrate bone immovably united to cranial arches. Anal open- 
ing round or longtudinal. Copulatory organ present, single. 
Key to families. 
a. Limbs developed as paddles, not capable of distinct movements at wrist 
or ankle-joint; digits flattened, elongated, bound immovably together by 
integument ; sea turtles. 
b. Feet scaleless, anteriorly large; carapace elongate. DERMOCHELIDA 
bb. Feet scaly; carapace heart-shaped. CHELONIID 
