MUSCULATURE. 269 



It extends forward along the margin of Ihe thoracic basket to the well-defined 

 linea alba at the midventral line. 



Muscles of throat and larynx. — Fewkes is apparently right in sup- 

 posing that Mivart has confounded the sternoglossus with the sternohyoideus 

 and sternothyroideus in his account of these muscles in the Echidna. It is 

 the most conspicuous of the throat muscles, and forms a stout round bundle 

 on each side of the pharynx. It arises from the dorsal side of the xiphisternum 

 and passes to the base of the tongue at the upper part of the pharynx, sending 

 a few fibers to the stylohyoideus as it crosses the larynx. As shown by Fewkes 

 in the case of the Echidna this muscle can be separated into two portions to whicli 

 he gives names. In addition, there is in the Proechidna a small thin muscular 

 band at about 25 mm. from the anterior end of the sternoglossus on its dorsal 

 side, that passes posterodorsally some 30 mm. to the pharyngeal wall. 



What appears to be a sternohyoideus arises in the Proechidna mainly from 

 the dorsal side of the manubrium. It forms a single median muscle and inserts 

 into the posterior end of the bodj^ of the hyoid. Westling attempts to homolo- 

 gize the sternoglossus of the Echidna with the sternohyoideus of other animals. 

 Neither this author nor Fewkes mentions the median muscle here considered 

 the sternohyoideus, nor is it clear that this muscle is present in a similar manner 

 in the Echidna. 



The sternothyroideus of the Proechidna likewise presents a few points of 

 difference in comparison with that of the Echidna. It arises from the anterior 

 dorsal edge of the manubrium instead of from the entire dorsal surface of the 

 sternrnxv. It passes forward as a thin band closely applied to the ventral sur- 

 face of the sternoglossus. About halfwaj^ on its length it becomes tendinous and 

 receives a short slip of muscle from the side of the sternohyoid. Continuing 

 forward, it again becomes muscular and inserts into the side of the thyroid 

 cartilage. 



The omohyoideus is present as in the Echidna. It arises at the antero- 

 internal edge of the middle portion of the scapida and tapers to its insertion 

 at the anteroventral border of the thyroid. 



The stylohyoideus is similar to that of the Echidna, arising from the jugular 

 process just behind the ear. It expands greatly in pa'ssing back to its inser- 

 tion at the midline of the larynx where it is joined by a raphe to the corre- 

 sponding muscle of the opposite side. 



The geniohyoideus is a rather narrow muscle from the symphysis to the 

 anterior end of the larynx, where it expands to a width of some 15 mm. It is 



