General Osteology. 23 



cervical, and often on the crest of the occipital bone also : it 

 is represented in Bimana by a condensed band of the fascia 

 nuchalis. The Rihs correspond in number with the dorsal 

 vertebrae ; and each rib is usually connected, by its head with 

 an articular cavity, formed by the bodies (cf. xi.) of two ver- 

 tebrae, and in addition (cf. xv.), backwards, by a tubercle, with 

 the transverse process of the posterior of those two vertebrae. 

 The continuations of the ribs by which they are united to the 

 sternum remain in most Mammalia cartilaginous (cf. xi. xiiL 

 XV.) during the whole of life (= costal cartilages). The ante- 

 rior ribs usually extend as far as the sternum*; in which 

 respect Mammalia differ from Aves. The Sternum is usually 

 narrow, and consists of a simple longitudinal series of bones, 

 instead of having the second, third, fourth and fifth segments 

 fused, as in the adult Man. There is generally no epi- 

 sternum. The manubrium sterni presents considerable dif- 

 ferences, but generally receives the clavicles when present, 

 and the two first ribs (cf. iii. iv. xv.). The ensiform pro- 

 cess varies both in length and shape (cf. v. xiii.). The 

 Lumbar vertebrae are generally the larger, and vary in num- 

 ber from three to seven. A well defined Sacrum is generally 

 present (cf. xi. xii.) : as a rule it is very narrow (cf. i. ii.) 

 and is composed of from two to five vertebrae, generally united 

 (cf. XV.) together, and not anchylosed inferiorly to the pelvis 

 (cf. xiii.). The sacrum in Bimana retreats backwards, and 

 makes an angle with the lumbar vertebrae ; in the rest of the 

 Mammalia, on the contrary, it lies nearly, in the same plane 

 with the lumbar vertebrae, and is hence said to be ''straight.'* 

 Caudal vertebrae are generally present (cf. i. ii.): the anterior 

 ones are similar to those in other series, most of the usual pro- 

 cesses being present, f and generally inferior processes also, 

 [= haemapophyses, or " Chevrori' bones] articulated with the 



* Exc. Bradypus tridactylus. f The pleurapophyses are absent altogether. 



