100 VERTEBRA OF THE CROCODILE. 



The lumbar vertebras are those in whicli the diapophy- 

 ses cease to support the movable pleurapophyses, although 

 they are elongated by the coalesced rudiments of such 

 which are distinct in the young crocodilia. The length 

 and persistent individuality of more or fewer of these 

 rudimenial ribs determines the number of the dorsal and 

 lumbar vertebrse respectively, and exemplifies the purely 

 artificial character of the distinction. The number of 

 vertebrae or segments between the skull and the sacrum, 

 in all the crocodilia I have yet examined, is twenty -four. 

 In the skeleton of a gavial, I have seen thirteen dorsal 

 and two lumbar; in that of a crocodilus cataphractus, 

 twelve dorsal and three lumbar; in those of a crocodilus 

 acutus and alligator lucius, eleven dorsal and four lumbar, 

 and this is the most common number; but in the skeleton 

 of the crocodile, probably the species called croc, bipor- 

 catus, described by Cuvier, he gives five as the number 

 of the lumbar vertebrae. But these varieties in the de- 

 velopment or coalescence of the stunted pleurapophysis 

 are of little essential moment ; and only serve to show 

 the artificial character of the "dorsal" and "lumbar" 

 vertebras. The coalescence of the rib with the diapophy- 

 sis obliterates of course the character of the "costal 

 articular surfaces," which we have seen to be common to 

 both dorsal and cervical vertebra3. The lumbar zygapo- 

 physes have their articular surfaces almost horizontal, 

 and the diapophyses, if not longer, have their antero- 

 posterior extent somewhat increased ; they are much de- 

 pressed, or flattened horizontally. 



The sacral vertebri'e are very distinctly marked by the 

 flatness of the coadapted ends of their centrums; there 

 are never more than two such vertebrae in the crocodilia 

 recent or extinct: in the first, the anterior surface of the 



