264 ZAGLOSSUS. 



angle. Possibly this anterior part maj- represent an acromio-clavotrapezius 

 The insertion seems to be slightly less extensive in the Echidna. 



The posterior portion of the trapezius, perhaps the homologue of the spino- 

 trapezius is a flat sheet, nearly an equilateral triangle in outline, arising by a 

 very thin tendinous sheet from the dorsal spines of the tenth thoracic to the 

 second lumbar vertebrae. It thickens greatly as it narrows to its insertion, 

 some 20 mm. in length, on the anterior edge of the scapula (the region corre- 

 sponding to the spine). 



As in the Echidna, the rhomboideus is a single muscle, arising under the 

 trapezius from the parietal margin of the skull, above and slightly in advance 

 of the ear, nearly to the midline of the cranium, and posteriorly underneath 

 almost the entire length of the trapezius. It thickens as it passes laterally to 

 its insertion along the entire vertebral border of the scapula. 



The levator scapulae ventralis arises by two heads: — (1) a slightly tendinous 

 attachment from the basioccipital and (2) a strong muscle mass from the ventro- 

 lateral portion of the atlas and axis. The insertion is at the anterior edge of 

 the scapula at the point of union with the clavicle and thence dorsally for about 

 20 mm. Mivart (1866) in the Echidna did not note the extension of the origin 

 to the axis, but otherwise the muscle appears to be similar. 



The occipitoscapularis is a narrow ribbon-like muscle from the mastoid 

 region just posterior to the ear. It is inserted along the vertebral edge of the 

 scapula, beginning about 10 mm. from the gleno-vertebral angle and extending 

 anteriorly about twice that distance. Apparently Mivart (1866) andWestling 

 (1890) cUd not find this muscle in the Echidna. 



The cleidomastoideus is wanting as in the Echidna. 



The latissimus dorsi has already been mentioned in connection with the 

 cutaneous muscles. It may be considered as consisting of three parts of which 

 the most anterior only has the usual relations. This arises by six or seven digi- 

 tations from the first seven thoracic vertebrae, and passes to a strong tendon 

 that inserts upon the most posterior part of the tuberosity of the humerus. Its 

 tendon is joined by that of a narrow muscle arising from the ridge on the scapula 

 dorsal to the glenoid cavity. This latter muscle is of doubtful homology, and is 

 found likewise in the Echidna where, however, it originates instead "from the 

 posterior extremity of the vertebral margin of the scapula." Mivart calls it 

 a dorso-epitrochlear (?), or possibly a separate portion of the teres major. West- 

 ling (1889, p. 14), however, considers it a part of the latissimus dorsi that is 

 not homologous with any separate muscle in other animals. In support of 



