XII. II 



MUSCLES OF THE BACK 



3i9 



though forming a continuous band, is crossed by a tendinous inter- 

 section, showing its segmental origin. At the hind end the coccygeo- 

 sacralis and coccygeo-iliacus muscles brace the urostyle on the pelvic 

 girdle. 



The pectoral girdle is attached to the axial skeleton by a series of 

 muscles. Rhomboid and levator scapulae muscles run from the supra- 

 scapula to the vertebrae and skull. The cucullaris muscle corresponds 



rect. 



Fig. 189. Muscles of larval Amby stoma. A, b, and c show successive layers. 



ep. epaxial muscles; ext.o. external oblique; h. horizontal septum; hyp. hypobranchial 



muscles; int.o. internal oblique; my. myocomma; rect. rectus abdominis; tr. transversus 



abdominis. (From Ihle, after Maurer.) 



to the mammalian sternomastoid, running from the skull to the 

 suprascapula; it is derived from lateral plate musculature and in- 

 nervated by the vagus. The naming of these muscles of the scapula, 

 and indeed all amphibian muscles, meets the difficulty that many of 

 the bundles of fibres are similar in their general course to muscles 

 found in mammals and yet differ sufficiently to raise serious doubts 

 about the wisdom of using the mammalian names. The similarity of 

 arrangement of the limb muscles is so striking throughout the tetra- 

 pods that there is probably no harm in keeping to the well-established 

 system of names, but we know so little of the hereditary or mechanical 



