xrii 



I'lni^lM (iloKDATA 



3r,.5 



there is no tiue symphysis, as their extremities remain cartilaginous 

 A hypo-ischiiun is not present. In the tarsus (Fig. 998) 

 there are two proximal bones — an adraijalo-scaphoid and a 

 cah-anmm — the latter having a prominent calcaneal process, 

 and two distal tarsal bones, together with a thin plate of 

 cartilage supporting the first and second metatarsals. The 



missing fifth digit is re- 

 presented by a rudimentary 

 metatarsal. 



Digestive Organs. — The 

 form and arramrement of the 



i'lG. !»iis. — Tarsus of Crocodile (right side) 

 from aljove. F. filjula ; T. tibia ; t !. c. tho 

 ^ astragalus, formed of the united tiblale, 



intermedium and ceiitrale ; /. fibulare 

 (calcaneum) ; 1 — 3, united first, second 

 and third distal tarsals ; 4, fourth tarsal ; 

 J—1 V, first to fourth metatarsals ; V!, fifth 

 distal tarsal and fifth metatarsal, (i'rom 

 Wiedersheim's Comparative Anatoiiii/.) 



Fiii. 997.— Pelvis of young Alligator, ventral 

 aspect. B, fibrous band passing between the 

 Ijubic and ischiadic symphyses ; BK. last pair 

 of .abdominal ribs ; F. oljturator foramen ; 

 G. acetal.)ulum ; 11. iluuu ; h. ischium ; M. 

 fibrous membrane between the anterior ends 

 of the two innominate bones and the last pair 

 of abdominal ribs ; P. pubis ; Sy. ischiadic 

 s^TUDhysis ; 1, II, first and second sacral 

 vertebra;. (Fi'om 'Wiedersheim's Comixtratice 

 AnatOidii.) 



teeth already described in the 

 account of Lacerta prevail in 

 the majority of Lizards. In 

 some of them the palatine 

 teeth are absent. The teeth 

 are sometimes fixed by their 

 bases to the summit of the 

 ridge of the jaw {acrodont 

 forms), sometimes fixed by their sides to tlie lateral surface of 

 the ridge {'pleurodont) ; they are never embedded in sockets 

 in any recent form. A Mexican Lizard, Hdodcnua, differs 

 from all the rest in havino- teeth which are grooved for the 

 ducts of poison-glands. In the Snakes (Figs. 988, 989) teeth 

 are rarely developed on the j)remaxilhe, but are present on the 

 maxilke, ]:ialatiucs and pterygoids, as well as the dentary of 

 the mandible. They may be of the same character through- 

 out, solid, elongated sharp-pointed teeth, which are usually 



