VIIL] THE MUSCLES. 317 



sterno-hyoid even in the Platypus. It may, as in the Great 

 Ant-eater, take origin as far back as the eighth bone of the 

 sternum. 



The omo-hyoid may be wanting even in Mammals, as e.g. 

 in the Dog. We find it, however, in Reptiles and Batrachians, 

 though absent in Birds. It may arise from the clavicle (as 

 Iguana), from the pre-coracoid (as Menobranchus], or be 

 bent at almost a right angle, looping round the sterno- 

 mastoid (as in the Chameleon). 



1 8. In the VERTEBRAL REGION there may be three scaleni 

 muscles, as in man, or but one. They may vary also as to 

 the number of ribs from which they take origin, and may 

 reach even to the basi-occipital (as in the Agouti), or to the 

 mastoid process (as in the Dolphin). They may be plainly 

 but a continuation forwards of the levatores cost arum, as in 

 Birds. 



They may be feebly developed, as in Reptiles, extending as 

 in Iguana from the first four cervical vertebras, or from the 

 atlas, to the first cervical rib, as in Iguana and Chameleo. 

 Finally, the scaleni may be indistinguishably blended with 

 the dorsal muscular mass, as in Batrachians and Fishes. 



The rectus capitis anticus major may attain a much greater 

 development than in man, extending down to the sixth dorsal 

 vertebra. 



The longus colli may arise as far back as the seventh 

 dorsal vertebra, as in the Agouti. 



We may have in Chelonians (e.g. Emys] a very elongated 

 muscle extending from even the hindmost thoracic vertebras 

 and going to the basi-occipital, and beneath this a series of 

 little muscles (extending each from one vertebra to the next 

 but one in front) connecting together the cervical vertebras 

 and the anterior dorsal ones. 



Again, we may have a simple muscular mass answering 

 apparently to both longus coitus and rectus anticus. Thus 

 in the Chameleon we have such a muscle arising from the 

 first eight or nine vertebras, and going to the basi-occipital. 

 The origin may be much more extensive in Serpents (where 

 the hypapophyses afford points of origin), and in certain 

 Batrachians (e.g. Menopoma and Menobranchus) a corre- 

 sponding muscle stretches on each side from beneath the 

 basis cranii throughout the whole trunk, and, diminishing 

 backwards, ends (or rather arises) in the sub-vertebral part 

 of the pelvic region. 



The rectus lateralis is really but the highest of the inter- 



