5 82 



REPTILES. 



connected with the quadrates." The quadrate articulates with the 

 pro-otic, for there is no squamosal. 



Example. — Typhlops, very widely distributed. 

 In all other Ophidians the palatines are widely separated, and their 

 long axes are longitudinal ; there are transverse bones connecting 

 palatines and maxillfe ; the pterygoids are connected with the 

 quadrates. 

 Sub-order z. Colubriformes (innocuous snakes). The poison gland 

 is not developed as such ; the maxillary teeth are not grooved. 

 Examples. — The British smooth snake (Coronella /avis); the 



British grass snake (Tropido- 

 nolus natrix) ; the Pythons ; 

 the Boas, of which the An- 

 aconda (Boa murina) (30 feet) 

 is the largest living Ophidian. 

 Sub-order 3. Colubriformes Venenosi. 

 Examples. — Cobras, Naja tripu- 

 dians (Indian), Naja haje 

 (African) ; the Hamadryad 

 (Ophiophagus daps), eating 

 other snakes ; Coral - snakes 

 (Elaps, etc.) ; Sea-snakes 

 (Hydrophis, etc.), with paddle- 

 shaped tails. 

 Sub-order 4. Viperiformes. 



Examples. — The British adder 

 (Pelias berus) ; the rattlesnake 

 (Crotalus), with a rattle 

 formed chiefly from epidermic 

 remnants of successive slough- 

 ings ; the African Puff-adder 

 ( Clotlio arietans). 



Fig. 253. — Lower surface of 

 skull of a young crocodile. 



p.mx., Premaxilla ; mx., maxilla 

 pal. , palatine ; o.t., os trans 

 versuin ; pt. , pterygoid ; /. , jugal 

 Qj., quadrato-jugal ; Q., quad 

 rate; p.n. 7 posterior nares ; c. 

 condyle. 



Crocodilia. Crocodiles, 

 Alligators, Gavials. 



General Characters. — The 

 Crocodilians are carnivorous fresh- 

 water reptiles of large size, now 

 represented by a few genera, e.g. 

 Crocodilus, Alligator, and Gavialis. 



The skin bears epidermic scales, underneath some of which 

 there are dermic bones or scutes. 



The tail is laterally compressed, and assists in swimming. 

 Teeth occur in distinct sockets in the premaxilla, maxilla, 

 and dentaries. 



Inmodern Crocodilians, almost all the vertebra are proccelous. 



