MAMMALS. 559 



s. cervicale) is attached, which in man is represented by merely a 

 condensed band of the fascia nuchalis. This ligament is in the 

 horse and the ruminants powerfully developed, and arises even 

 from the spinous processes of the lumbar vertebrae. In the car- 

 nivorous animals it arises from the posterior cervical vertebras, and 

 the first dorsal alone. Forwards it is attached to the spinous pro- 

 cess of the second cervical vertebra, and often to the crest also of 

 the occipital bone, above the large occipital foramen 1 . The sacrum 

 in man retreats backwards, and makes an angle with the lumbar 

 vertebrae; in the rest of the mammals, on the contrary, it lies 

 nearly in the same plane with the lumbar vertebrae, and is also 

 narrower than in the human skeleton. In the ox (and in most of 

 the rest of the ruminants) the spinous processes of the sacral ver- 

 tebrae coalesce to form a ridge, by which amongst other characters 

 the sacrum of the ox is markedly distinguished from that of the 

 horse. 



The last vertebras of the tail cease to have an arch ; their form 

 is that of the phalanges of the fingers or of a double cone, of which 

 the points are turned towards each other, as in an hour-glass. In 

 many, especially in long-tailed mammals (as Halmaturus, Dasypus, 

 Mam's, Myrmecophaga, also in the Cetacea), most of the caudal 

 vertebrae are furnished with inferior spinous processes, which pre- 

 sent the form of a V, and arise between two bodies of vertebrae. In 

 the beaver (Castor), in which the transverse processes in the tail 

 are very large, those lower spinous processes exceed the upper in 

 size. 



Each rib usually is connected in mammals by its head, with an 

 articular cavity formed by the bodies of two vertebrae 2 , and in 

 addition backward by a tubercle with the transverse process of the 

 posterior of those two vertebrae. In the monotremes, the ribs are 

 connected with the body of the vertebras alone. In the cetaceous 



1 In the elephant there is at this part a cavity with many projecting bony plates, 

 by which this ligament is attached more firmly; compare P. CAMPER Description 

 anat. (Tun Elephant, (Euvres, II. p. 177, PI. xx. fig. i, A, B, c, D; PI. xxiv. B, G. 



20, 3, H. 5. 



3 According to the observation of RETZIUS, these fovece costales belong originally to 

 the arches of the vertebrae, as may be seen in skeletons of children and young mam- 

 mals, where the bodies of the vertebrae are still separated from the arches by intervening 

 synchondroses. 



