326 



COMPARATIVE ANATOMY 



In marine Chelonians and Crocodiles there are no large glands 

 united into groups connected with the mouth, but in Testudo 

 grca there are well developed sublingual glands. 



Pterygosphenoidalis 

 ant. 



A 



Pterygo- 

 parietalis 



Retractor quadrati 

 r 



I 



Maxilla 



Fang -~ 



Transveo-maxillo 

 pterygo-mandibulais 



~^~_ ______ Quadrate 



Pterygosphen- 

 oidalis post. 



Mandible 



Palatine '* ~\ 



Pterygoid 



Pterygosphenoidalis post. 



Duct of poison-gland 

 Fang 

 - Zygomatic ligament 



-"Poison-gland and sheath 



3 Masticatory muscles 

 ~~ Zygomatic ligament 

 - Mandible 



Portion oj trans. -max. -pter.-mand. muscle 

 FIG. 238. HEAD OF THE VIPER (after Katheriner). 



A, from the left side : the integument, zygomatic ligament, poison-gland, jaw- 

 muscles, and palatine and pterygoid teeth are not indicated. B, left side 

 from below : the muscles of the jaw are cut through transversely, and part 

 of the sheath of the poison-gland is slit open. 



Birds. In Birds, and more especially in climbing Birds 

 (Scansores), a well-developed lingual gland is present opening on 

 the floor of the mouth, and another at the angle of the latter. 



