THE SPINAL COLUMN OF REPTILES. 159 



the spinal column into an amazing number 

 of distinct portions or vertebrae — the nature 

 of the articulation of thesQ vertebrae — and 

 the lax and peculiar attachment of the ribs. 

 With respect to the number of vertebras in 

 different snakes, it varies in different species, 

 and all, excepting the two or three first, and 

 those of the tail, are furnished with ribs. Pro- 

 fessor Jones enumerates three hundred and four 

 distinct vertebrae in the boa constrictor, of which 

 two hundred and fifty-two support ribs. The 

 spine of the common ringed snake is composed 

 of more than three hundred vertebrae, and that 

 of the rattlesnake of above two hundred. We 

 do not know that the vertebras in any of the 

 long, slender tree-snakes, have been counted, 

 but they must be extremely numerous. 



With respect to the articulations of these 

 vertebrae, Ave may observe that they are on 

 the principle of the ball-and-socket; and 

 in this manner both pliancy and strength are 

 combined. On examining each vertebra, we 

 find that its anterior extremity is hollowed 

 out into the form of a cup or deep depression, 

 while its posterior extremity is rounded into 

 a smooth and polished ball; this ball is re- 

 ceived into the cup at the anterior extremity 



