The appendicular muscles of Necturus maculosus. 391 



the linea alba while those of the extreme anterior margin are in- 

 clined sliglitly downwards as they pass out to the insertion. The 

 lateral myocommatous übers are reinforced from beneath (on the 

 dorsal side of the sheet) by small slips from myocommata 7 and 8, 

 but these reinforcements are not seen when the muscle is viewed 

 from its ventral aspect and become visible only by freeing the sheet 

 from its underlying connective tissue and reflecting it. 



From the above extensive origin the fibers converge to a re- 

 stricted fleshy insertion into the crista lateralis of the numerus, 

 at its apex and sliglitly upon the medial side. 



B. Muscles between the Shoulder girdle and the free limb. 



M. supracoracoideus (sc). This muscle and the next, to- 

 gether with M. dorsalis scapulae, are the three muscles that cover 

 the outer surfaces of the three subdivisions of the Shoulder girdle, 

 arising from these surfaces and inserting into the proximal epiphysis 

 of the numerus. This muscle is incompletely divisible into two 

 portions, of which the larger, or main, portion arises by a fleshy 

 origin covering the middle third of the outer surface of the carti- 

 laginous coracoid, and leaving free from musculai attachment a 

 portion about the free anterior margin, as well as the basal third, 

 that is, the part lying nearest the glenoid fossa. The second portion 

 of the muscle is continuous with the first along its antero-lateral 

 aspect and arises from the margin of the deep sinus between 

 coracoid and procoracoid, running up somewhat upon the base of 

 the latter. The two parts are blended along their entire extent, 

 ad insert as a Single muscle into Ihe crista lateralis of the 

 numerus, just proximal to the insertion of the pectoralis. 



M. procoracohumeralis (ph). This is the third and last 

 of the muscles that cover the outer surface of the separate elements 

 of the Shoulder girdle. It lies upon and nearly Covers the ventral 

 aspect of the procoracoid, leaving exposed only the free anterior 

 end of the cartilage. The surface of origin includes approximately 

 the anterior half of this piece, extending laterally and medially 

 from edge to edge. The distal half of this muscle, that lying to- 

 wards its insertion, is not attached to the cartilage and is separated 

 from it by the two slips of the rectus superficialis hypobranchialis 

 posterior, which differentiate from the trunk musculature upon either 

 side of the cartilage and run over its free edges to insert into its 



