SNAKES. 



15 



Order SQUAMATA— continued. 



b. Sub-order Lacertilia 

 tinued). 

 Family Anniellidce. 

 „ Helodermatidw. 

 „ Varanidce. 

 „ Xantusiidce. 

 „ TeiidcB. 

 „ Amphisbcenidce, 

 „ Lacertidw. 

 „ Gerrhosauridce. 

 „ Scincidm. 



(con- 



b. Sub-order Lacertilia (con- 



tinued.) 

 Family Anelytropidm. 

 „ DibamidcR. 



c. Sub-order Rhiptoglossa. 



Family Chamcdeontida. 



d. Sub-order Pythono- 



morpha. 

 Family Dolichosauridm. 

 Mosasauridm. 



Sub-order I. — Ophidia — Snakes. 

 (Cases 11-15.) 



As the distinctive characteristics of this group have been already Case 14. 

 given under the heading of the order Squamata, we may at once 

 pass to a brief survey of the more important families. 



The first family is that of the Boidce,, or Boas and Pythons, 

 among which are included the largest of living Snakes. The skeleton 

 retains vestiges of the pelvis and hind-limbs, and the latter are repre- 

 sented externally by small claw-like spurs near the vent (fig. 12). 

 On the upper surface the scales are usually small and smooth, but 

 those on the lower aspect form two broad series in advance of the 

 tail, and either a double or single row on the tail itself. In the 



Fig. 13. 



Skull of a Python ; J nat. size. (No. 291 ) 

 m, maxillary ; pm, premaxillary ; q, quadrate-bone. 



