BY W. J. S. McKAY 289 



Innervation. N. supracoracoideus (Fig. 13, et 16, 22 A.). 

 VVestling gives the same innervation. 



Echidna. 



Westling describes this muscle under the name of M. supra- 

 coracoideus, following Fiirbringer's nomenclature for the supposed 

 homologous muscle in Saurians. Westling gives the origin from 

 the ventral surface and lateral border of the epicoracoid, and the 

 insertion: "Tuberculum majus, oberhalb der Insertion des M. 

 pectoralis und medial von derselben, und lateraler Rand der 

 Vertiefung zvvischen beiden Tuberculi bis zur Insertion des M. 

 coraco-brachialis brevis hinab. Innervation: N. supracoracoideus." 



Westling then goes on to remark that the muscle is present in 

 Saurians, and that its origin in these is, as in the Monotremes, 

 from a well developed coracoid, and its insertion is likewise similar; 

 and quotes Fiirbringer's opinion that the homology between these 

 muscles in the Monotremes and Saurians is undoubted. 



IjECHE follows Westling, and describes the muscle with the 

 pectoral group ; and also in another place under " Muskeln am 

 Ol^erarme." 



MlVART was the first to describe the muscle in Echidna, under 

 the name of "epicoraco-humeral." After giving the origin and 

 insertion, he says, " the muscle answers neither by its origin nor 

 insertion to either the P. minor or to the subclavius. It is evi- 

 dently the muscle described and figured by Meckel as the anterior 

 portion of the deltoid, but in the Echidna we have, in addition 

 to this muscle, another which appears to be wanting in the Orni- 

 thorhynchus (judging from Meckel's figures), and which is evidently 

 the anterior part, if not the whole, of the deltoid. This muscle 

 may be the serial homologue of the pectineus or of the obturator 

 externus, more probably the former, on account of its insertion." 



OrNITHORHYNCH!'S. 



Owen describes this muscle under the name of " anterior part 

 of the deltoid," saying that it arises " from the anterior extremity 

 of the coracoid and is inserted on the deltoid crest." 



