and Structure of the Proteus Anguhnts. S 



has a peculiar form, possessing a dentiform process and articu- 

 lating surfaces, on which the condyles of the occiput rest. All 

 the others consist of a body, contracted in the middle like an 

 hour-glass, and, except towards the extremity of the tail, each 

 vertebra is furnished with four articidating apophyses, or pro- 

 cesses, two anterior, and two posterior. The two anterior pro- 

 cesses of each vertebra are covered by the posterior ones of the 

 vertebra above it ; and its two posterior ones cover, in turn, the 

 anterior processes of the vertebra below : so that, viewed from 

 above, the vertebrae seem to be placed in the manner of tiles. 



Beside these processes, all the vertebrae, except the atlas 

 and some of the caudal, have two transverse processes, which 

 vary a little in form in different parts of the spine. In the third 

 vertebra, these processes, which in the bone above were entire^ 

 separate into two portions of unequal length, and to the shorter 

 portion is attached the rifdiment of a rib. The same structure 

 is continued downward to the ninth vertebra, where this parti- 

 tion of the process ceases. Below the ninth vertebra, these trans- 

 verse processes are formed of two thin laminae united together, 

 and stand out from the body of the bone, like the unfledged 

 wings of a young bird. Gradually these laminae diminish and 

 disappear, so that about the third or fourth caudal vertebra 

 they exhibit only a simple spine; and this spine, continually be- 

 coming smaller, vanishes also about the tenth caudal vertebra. 

 In addition to these transverse processes, the vertebra of these 

 animals have also their spinous processes, which spring from the 

 extreme posterior and superior border of each vertebra. Beside 

 having the dorsal spinous processes, the caudal vertebrae are fur- 

 nished with two other spinous processes on the opposite surface of 

 the bone, and which, from their position, may be named ventral. 

 These spring from the roots of the transverse processes on each 

 side, and proceeding in a parallel course, very soon unite, and 

 form a canal, through which the bloodvessels, that a)-e distri- 

 l)uted to the tail, are continued. By the gradual dinsinution of _ 

 the processes, this canal is lost before reaching the extrcmil y of 

 the tail. 



So much for the bones of the cranium and spiuc. Of the ske- 

 leton there still remain the bones of the four extremities, the 

 s|)elvis, and the shoulder. But it would be tiri.hcjmi' and useleas. 



