viii.] THE MUSCLES. . ^, 



Horse) extends from the spines of the dorsal vertebrae to the 

 occiput, sending down a lamellar expansion to the spines of 

 the cervical vertebras. In the Giraffe it extends back even to 

 the sacrum. 



This ligament may become ossified, as in the Mole. 



The latissimus dorsi is another nearly constant muscle, 

 though of varying extent. It may, as in many Apes, send a 

 slip on to the olecranon, or even, as in the Echidna, to the 

 flexor carpi ulnaris with which it blends. It may be divided 

 into two parts, as is the case in the Echidna. It may arise 

 within the ribs, as in Chelonians, e.g. Emys. It may be 

 very small, as in Menopoma (Fig. 282). Finally, it may com- 

 pletely unite with the trapezius, as in Anguis fragilis, or it 

 may be altogether wanting. 



The rhomboidei may be more divided than in man, as in 

 the Mole ; or single, as in the Hawk ; or absent, as in the 

 Apteryx and apparently in lower forms. A rkomboideus 

 capitis, which sometimes exists in man, is often present in 

 lower forms, as e.g. in Lemur and Nycticebus. 



Levator anguli scapula. This is essentially and morpho- 

 logically the anterior part of that great muscle by which, in 

 quadrupeds, the trunk is slung between the summits of the 

 scapulas the greater part of which goes by the name of the 

 serratus magnus rather than a really distinct muscle. 



There is a muscle commonly existing in Mammals, but 

 which is developed only by rare exception in man. This 

 (the levator claviculcz) extends from the atlas to the scapula 

 or to the clavicle ; it is well seen in Apes. It is a muscle of 

 considerable constancy, as it is found of a very large relative 

 size in Reptiles, e.g. Iguana (Fig. 284). It may arise from 

 the occipital region, as in Chameleo. 



Another muscle, not found in man, but developed in some 

 Mammals (e.g. the Horse and Hyrax), is termed the sterno- 

 scapular. It extends from the sternum over the scapulo- 

 humeral articulation to the superior vertebral angle of the 

 scapula. 



The serrati postici superior and inferior are both repre- 

 sented in many Mammals by one single continuous muscle, 

 which seems to attain- its maximum of development in the 

 Hyrax. Only the inferior serratus posticiis may be present, 

 as in the Three-toed Sloth, while sometimes (as in the Bats) 

 it is the superior which is exclusively, or all but exclusively, 

 developed. 



The splenius capitis is a muscle the possession of which 



Y 



