134 



637. Two abdominal vertebrae of a Coluber (Coluber elapkus). 



They are characterized hy the great extent to which the part of the diapophysis that under- 

 props the zygapophysis is produced heyond the articular surface : the lower end of the diapo- 

 physis is less produced : the hypapophysis, beyond the anterior fourth part of the vertebral 

 column, is reduced to a straight ridge, extending along the middle of the under surface of the 

 centrum, and is not produced posteriorly : a groove separates the ridge on each side from the 

 diapophysis and the posterior ball of the centrum. Both the cup and ball and the articular 

 part of the diapophysis are relatively smaller than in the Naja ; the neural spine is lower in 

 proportion to its antero-posterior extent. 



Presented by Prof. Owen, F.E.S. 



Genus Deirodon. 



638. The skeleton of the rough Tree-Snake (Deirodon scaber). 



Its length is 1 8 inches ; the number of vertebrae 256 ; of which 1 90 support moveable ribs, 

 which are unusually slender. Hypapophyses are developed from thirty-two anterior verte- 

 brae ; these are directed backwards in the first ten vertebrae, and incline forwards in the last 

 ten, where they are unusually long, and tipped with a coat of hard dentine ; in the recent 

 snake they perforate the oesophagus and serve as teeth. The jaws appear to be edentulous, 

 but are roughened by anchylosed, minute rudiments of teeth. This modification of the dental 

 system, with the singular development of the cervical hypapophyses, relates to the nature of 

 the food of the Deirodon : it lives in trees, and feeds habitually upon the eggs of small birds : 

 the minutely roughened jaws assist in the introduction of the egg into the mouth, and its 

 transference entire into the gullet : had teeth been developed of the ordinary size and shape, 

 and in the jaws, the egg would have been broken, and much of its contents lost, but this does 

 not happen until it meets, in the progress of deglutition, with the anteriorly directed cesopha- 

 geal teeth ; these saw through the shell, the egg is crushed by the contraction of the oeso- 

 phagus and surrounding muscles, and its contents transferred entire to the stomach. 



Presented by Dr. Andrew Smith, F.L.S. 



Genus JEryx. 



639. Two abdominal vertebrae of an African species of Eryx. 



In these the diapophysis does not extend beyond the articular surface of the anterior zyg- 

 apophysis, but is exclusively devoted to forming a low, subconvex, articular tubercle, which 

 has a longitudinal depression anteriorly ; the posterior margin of the neurapophysis forms an 

 angle above the zygantrum, which angle, though slight, is more marked than in any of the 

 foregoing Ophidians ; the hinder end of the hypapophysial ridge is slightly produced ; the 

 zygapophyges are less extended outwards than in the Pythons. 



Presented by Tftomas Keate, Esq. 



