622 



OPHIDIA COLUBRIDAE 



CHAP. 



shield, cov^eriiig the end of the snout, is mvich broader than high. 

 The coloration is variable, hut there is always a pair of elongated 

 blackish spots or a U-shaped mark on the nape. 



Sub-Fam. 3. Rhachiodontinae. — With only a few teeth on 

 the posterior part of the niaxillaries, on the palatines and 

 dentaries. Some of the vertebrae in the retdon of the lower neck 

 have strongly developed hypapophyses, which are directed forwards 

 and pierce the oesophagus. They are used for filing through or 



Fig. 166. — Dasypdtis scdbra. x h 



breaking the birds' eggs which seem to be the chief food of these 

 snakes. 



I)asi/2)eltis scabra, the only species, inhabits Tropical and South 

 Africa ; altliough it reaches scarcely more than two feet and a. 

 half in length, such a specimen is able to swallow an ordinary 

 fowl's egg. I'igeons' eggs are swallowed by snakes little more 

 than one foot in length, which seems at first sight quite im- 

 possible. Tlie swallowed egg distends the skin to its utmost 

 capacity ; it then slides down further, the snake makes some 

 slight contortions and the swelling collapses ; after a while the 

 l)rokeu and sucked-out shell is vomited out as a crumpled up 



