v.] EDENTATA. 61 



The mode of ossification of the thoracic and lumbar 

 vertebrae of the Cetacea appears, so far as it has been 

 ascertained, to differ from that of all other Mammals, inas- 

 much as the neuro-central suture (see Fig. 20) is always 

 placed a little above the junction of the arch and the body, 

 the whole of the latter, with any process which may arise 

 from it, being ossified from the central nucleus. Conse- 

 quently, in the thoracic vertebne of the Dolphins, the trans- 

 verse process is anteriorly an outgrowth from the arch, then 

 partly from the arch and partly from the body, and finally 

 from the body alone a condition quite unknown in other 

 Mammals. 



It would appear, from the conflicting statements on the 

 subject, that the transverse processes of the lumbar region 

 are sometimes ossified autogenously, and sometimes exo- 

 gcnously from the centrum. 



The members of the order EDKNTATA present some great 

 peculiarities in the condition of the trunk vertebrae, especially 

 those of the lumbar region. 



As to numbers, the Three-toed Sloths (Bradypus) have 

 19 altogether (either 16 and 3, or r$ and 4); and the Two- 

 toed Sloths (C/iola'pus) have sometimes as many as 24 tho- 

 racic and 3 lumbar, making altogether 27 trunk vertebrae. 

 The great Anteater (Afyrwecophaga) has 18 (15 and 3. 

 R. Coll. Surg. ; 1 6 and 2, Mus. Cam.) ; the little Two-toed 

 Anteater (Cydothurus\ 17 (15 and 2). The Armadillos 

 have 14 to 16, the Pangolins (Manis) commonly 18 to 21 

 and the Cape Anteater (Oryctcropus) 21 (13 and 8). 



The vertebral column of the Sloths is remarkable for th e 

 extremely broad, flat laminae and short neural spines, lyin 

 backwards on the next succeeding vertebrae, throughout the 

 whole column down to the sacrum. All the processes are 

 very short, and the spines are bifid in the lumbar region. 



