268 ZAGLOSSUS. 



medially from the manubrium to the large third sternebrum. Its fibers pass like- 

 wise in a stout bundle to an insertion on the pectoral ridge of the humerus, 

 slightly posterior and lateral to the insertion of the edopectoralis. In the Echidna 

 the separation of the edopectoralis from eniopedoralis seems much less clearly 

 marked, if indeed, it is to be distinguished at all. A third portion seems to 

 represent a xiphihumeralis. It arises as a narrow muscle at the median line, 

 from the xiphisternum, whence it extends posteriorly about 25 mm. It passes 

 obliquely forward and inserts on the pectoral ridge at the caudal end of the 

 greater tuberosity of the humerus. 



In addition to these, there is a large muscle that arises along the entire 

 anteroventral edge of the clavicle from the articulation with the scapula 

 nearly to the median line. Its insertion is likewise on the pectoral crest con- 

 tinuous with and slightly anterior to that of the eniopedoralis. This muscle 

 both Mivart and Westling find in the Echidna. The former considers it a part 

 of the deltoid on account of its proximity to the acromion at the dorsal point 

 of origin. This interpretation is accepted with some misgiving bj' Westling, 

 who suggests that it may almost equally well represent a davopedoralis, a view 

 that seems quite as probable. 



The abdominal muscles present no special peculiarities, but are essentially 

 similar to those of the Echidna. The redus abdominis is a strong band of muscle 

 fibers some 20 mm. wide, from the base of the epipubic bone passing forward 

 on each side to insert on the ventral prominence of the coracoid and on the 

 A-entral half of the first rib. 



The obliquus exlernus is strongly develojied, and overlies the posterior 

 half or more of the preceding muscle. It arises from the anterior edge of the 

 pubis and the epipubic bone, the tuberosity of the ilium and the lumbar verte- 

 brae, and by a series of muscle strips from the second to the last rib. Each of 

 these strips arises just proximal to the union with the sternal portion of the rib 

 and hence the origins become successively higher dorsally, in pas.sing posteriorly. 

 These strips are all united by fasciae, and between the pubis and the thoracic 

 basket the muscle forms- a continuous sheet of fibers, that becomes thickest 

 over the abdomen and is joined as usual to the corresponding muscle of the 

 opposite side. 



The obliquus internus is in intimate connection with the fibers of the trans- 

 rersus abdominis from which it is hardly to be separated.- The latter is likewise 

 closely connected with the obliquus exlernus along the lumbar and peh^ic origin. 



