444 MANUAL OF ZOOLOGY SECT. 



of the same nature throughout solid elongated sharp- 

 pointed teeth, which are usually strongly recurved, so that 

 they have the character of sharp hooks, their function being 

 rather to hold the prey and prevent it slipping from the 

 mouth while being swallowed than to masticate it. Non- 

 venomous Snakes possess teeth only of this character. In the 



cl 

 episl 



FIG. 252. Pectoral arch and sternum of a Lizard (Lacerta agilis). cl. clavicle ; cor. 

 coracoid ; ep. cor. epicoracoid ; epist. episternum ; glen, glenoid cavity for head of 

 humerus ; pr. cor. procoracoid ; r.i r.4, first to fourth sternal ribs ; sc. scapula ; 

 st. sternum ; supra, sc. supra-scapula. (After Hoffmann.) 



venomous Snakes more or fewer of the maxillary teeth as- 

 sume the character of poison-fangs. These are usually much 

 larger than the ordinary teeth, and are either grooved or per- 

 forated by a canal for the passage of the duct of the poison- 

 gland. In the Vipers there is a single large curved poison-fang 

 with small reserve-fangs at its base, these being the only teeth 

 borne by the maxilla, which is very short (Fig. 251) ; in the 

 venomous Colubrine Snakes the poison-fangs are either the 



