238 THE ANATOMY OF VERTEBKATED ANIMAl-S. 



of the vertebra for the capitulum of the rib, while the tipper 

 part of the neural arch gives off a more elongated transverse 

 process for the tuberculum. Thus the transverse processes of 

 ail the dorsal vertebrae of a bird resemble those of the two an- 

 terior dorsals of a crocodile, and no part of the vertebral col- 

 umn of a bird presents transverse processes with a step for 

 head of the rib, like those of the great majority of the vertebrae 

 of Grocodllia, Dlnosauria, Dicynodontia, and Pterosauria. 



The discrimination of the proper lumbar, saoral, and ante- 

 rior caudal vertebrae, in the anchylosed mass which constitutes 

 the so-called " sacrum " of a bird, is a matter of considerable 



^7/ 



Pio. 80. — The "Sacram" of a Chick, dl^ dorso-lumbar ; «., sacral ; c, caudal vertebne. 



difl&oulty. The genei'al arrangement is as follows : The most 

 anterior lumbar vertebra has a broad transverse process, which 

 corresponds in form and position with the tubercular trans- 

 verse process of the last dorsal. In the succeeding lumbar 

 vertebrse this process extends downward ; and, in the hinder- 

 most, it is continued from the centrum, as well as from the 

 arch of the vertebra, and forms a broad mass which abuts 

 against the ilium.* This process might well be taken for a 

 sacral rib, and its vertebra for the proper sacral vertebra. 

 But, in the first place, I find no distinct ossification in it ; and, 

 secondly, the nerves which issue from the intervertebral fora- 

 mina in front of and behind this vertebra enter into the lum- 

 bar plexus, which gives origin to the crural and obturatoi 

 nerves, and not into the saoral plexus, which is the product of 

 the nerves which issue from the intervertebral foramina of the 

 proper sacral vertebras in other Vertebrata. Behind the last 

 lumbar vertebra follow, at most, five vertebras, which have no 

 ribs, but their arches give off horizontal, lamellar, transverse 

 processes, which unite with the ilia. The nerves which issue 

 from the intervertebral foramina of these vertebrae unite to 



* It would be more proper to say that oaaifioation extends into it from the 

 centrum as well as from tne neural arch. The process, like other processes, 

 eiists before the centrum is differentiated from the arch by ossifioation. 



