REPTILES. 



291 



of the face begins, and as the backward inclination of the 

 teeth allows the food only to move in one direction, it is 

 gradually drawn, by a constantly shifting of the hold on 

 either side, into the throat. 



There is a South African Snake (Deimdon), the mouth 

 of which is deprived of teeth, yet it is destined to feed on 

 the eggs of birds. The apparent defect in this case has 

 been pointed out by Professor Owen as a beautiful example 

 of special contrivance. " If," observes that great physiolo- 

 gist, " the teeth had existed of the ordinary form and pro- 

 portion in the maxillary and palatal regions, the egg would 

 have been broken as soon as it was seized, and much of its 

 nutritious contents would have escaped from the lipless 

 mouth of the Snake in the act of deglutition; but owing 

 to the almost edentulous state of the jaws, the egg glides 

 along the expanded opening unbroken, and it is not until 

 it has reached the gullet, and the closed mouth prevents 

 any escape of the nutritious matter, that the shell is ex- 

 posed to instruments adapted for its perforation. These 

 instruments consist of the inferior spinous processes of the 

 seven or eight posterior cervical vertebrae, the extremities 

 of which are capped by a layer of hard cement, and pene- 

 trate the dorsal (upper) parietes of the oesophagus; they 

 may be readily seen even in very young subjects, and in 

 the interior of that tube, in which their points are directed 

 backwards. The shell being sawed open longitudinally by 

 these vertebral teeth, the egg is crushed by the contractions 

 of the gullet, and is carried to the stomach, where the shell 

 is no doubt soon dissolved by the gastric juice."* 



It might be expected that the ferocity of animals so 



* " Odontography." 



