48 ANATOMY OF VERTEBRATES. 



mechanical connections of the parts ; but, by the intervention of 

 long and slender tendons, the quantity of the contractile fibre is 

 duly apportioned to the extent of motion required for the larynx 

 and os hyoides. The ' omo-hyoideus ' was adjusted to its office by 

 a more simple modification ; instead of having a remote origin from 

 the shoulder-blade, its fixed point of attachment was brought for- 

 ward to the nearest bone (the third cervical vertebra) from which 

 it could act upon the hyoid to the due extent. 



In all Herbivora the muscles more directly worked in masti- 

 cation, e. g. the ( masseter ' and 6 pterygoidei,' are proportionally 

 more developed than the biting muscles, e. g. * temporales ; ' but 

 there are degrees of difference ; in those Ungulates in which the 

 canines are most developed, as e.g. the Hog and Camel tribes, 

 the temporal muscles are larger. In all Ungulates the chief 

 depressor of the jaw, or opener of the mouth, passing from the 

 paroccipital to the mandibular angle, has a single fleshy belly ; 

 it is, however, the homologue of the ' digastricus ' in Man. 



One of the muscles proceeding from the neural arches of the 

 dorsal vertebras to the occiput is tendinous, along a portion of its 

 mid-course, in most unguiculate Mammals : it is called ' biventer 

 cervicis ' in Anthropotomy. Contiguous muscular fasciculi ex- 

 tending from the neural spines of the anterior dorsals to those 

 of more or less of the cervical series, are termed ' spinalis cervicis.' 

 The pair of fibrous masses with like attachments, but in which the 

 striated fibre is almost wholly reduced to the yellow elastic tissue 

 in Ungulates, is commonly known as the ' ligamentum nuchas.' 



In the Giraffe this mechanical stay and support of the long 

 neck and head commences from the sacral vertebrae, and receives 

 fresh accessions from each lumbar and dorsal vertebra, as it 

 advances forward; the spines of the anterior dorsal vertebrae 

 become greatly elongated to afford additional surface for the 

 attachment of new portions of the ligament, which appears to be 

 inserted, on a superficial dissection, in one continuous sheet into 

 the longitudinally extended but not elevated spines of the cer- 

 vical vertebrae, as far as the axis ; the atlas, as usual, is left free 

 for the rotatory movements of the head; the ligament passes 

 over that vertebra to terminate by an expanded insertion into 

 the occipital crest. It consists throughout of two bilateral 

 moieties. In the specimen I dissected, the nuchal ligament, 

 in situ, measured 9 feet in length : an extent of 6 feet was re- 

 moved, which immediately contracted to 4 feet. 



In the Camel the ligamentum nuchae arises, broad and thin, from 

 the anterior dorsal spines, but gathers substance as it advances and 



