410 SPANISH -TOWN. 



These are valves that shut in the throat. We are led 

 to conclude on first seeing these valves that we 

 are examining an animal that has no tongue, and 

 that the underfold of what we are inspecting is the 

 rudimentary trace of that member cut out. This, 

 however, with the corresponding curtain above it in 

 the roof of the mouth, forms an apparatus that closes 

 the distending aperture of the throat, and permits 

 the reptile to hold its prey and drown it, without 

 being itself liable to be drowned. 



" Between the branches of the lower jaw, a certain 

 degree of muscularity is perceived in the yellow floor- 

 ing of the mouth. This is the representative of the 

 tongue. The thickened membrane shows its lingual 

 analogue, though destitute of all approach to a red 

 colour, by its rough glands and pores giving out 

 saliva. 



" The nostrils, placed at the extremity of the snout, 

 terminate in a post-oral cavity, by passages that com- 

 municate with the throat behind the valvular appa- 

 ratus we have been describing. This is a provision 

 for respiration when the valves are closed, which at 

 once renders intelligible and necessary a remarkable 

 structure of the fauces by which the upper jaw seems 

 to move upward, whilst the under one retains its 

 horizontal position. The lower is prolonged behind 

 the skull to a great depth. On raising the head at 

 an angle, the upper jaw appears to move upward, and 

 the under jaw to remain immovable. The upper 

 jaw does indeed move upward, but not independently. 

 On casting back the head, an acetabulum of the 

 united skull and jaw acts on a condyle of the lower 



