66 



ANATOMY OF VERTEBRATES. 



54 



more downward, so as to form the body of the rib, which termi- 

 nates, however, in a free point. In the ninth cervical, the rib, i, 

 is increased in length, but is still what would be termed a ' false ' 

 or ' floating ril) ' in anthropotomy. 



In the succeeding vertebra the pleurapojihysis, fig. 54, /.•, 

 articulates with a hjcmapophysis, and 

 the haemal arch is completed by a 

 hajmal spine; by which completion 

 of the typical segment we distinguish 

 tlie commencement of the series of 

 dorsal vertebri-c. With regard to the 

 so-called ' 2:)erforation of the transverse 

 process ' this equally exists in the pre- 

 sent vertebra, as in the cervicals ; on 

 the other hand, the cervical vcrtebraj 

 equally show surfaces for the articu- 

 latidu of ribs. The typical characters 

 of the segment, due to the completion 

 of both neural and liannal arclies, are 

 continued in some species of Crocodilia 

 to tlic sixteenth, in some { Crocodilus 

 acutns) to the eighteenth vertebra. In 

 the Crocodilus acutus and the Alligator 

 luciiis the hremapophysis of the eighth 

 dorsal rib (seventeenth segment from 

 the head) joins that of the antecedent 

 vertebra. The jdeurapophyses ]iroject 

 freely outward, and become * floating 

 riljs ' in the eighteenth, fig. 55, h, 

 nineteenth, ib. c, and twentieth, ib. d, 

 vertebra\, in which tliey liecome rapidly 

 shorter, and in the last appear as mere 

 appendages to the end of the long and 

 broad diapophyses : but the hwmapo- 

 ])hyscs by no means disappear after 

 the solution of their union with their 

 ])leuraj)ophyscs ; tliey are essentially 

 independent elements of the segment, and are according! v con- 

 tiniied, in ])airs, fig. 55, 3, 4, 5, f,, 7, and 56, along the ventral sur- 

 face of tlie abdomen of the Croeodilin, as far as their modified 

 liomoty])es the ynd.iic l)oncs,ib. 8. Tliey are more or less ossified, 

 and are generally divided inio two en- three iiieces. A sboi't carti- 

 laginous piece, an unossificd jiart of the iikMu-ajiopliysis, intervenes 



r)i;icnviii) uf niilr 



