356 
DE. E. W. SHUEELDT’S MOEPHOLOQICAL 
third ; at its origin its fibres spread out fan-fashion, their terminal 
ends meeting those of the muscle of the opposite side in the 
median line. Here it is quite adherent to the skin, but its fibres 
rapidly converge as they pass in the direction of the shoulder-joint, 
opposite which region they gradually free themselves from the skin 
to form a small fusiform muscle, which, ending in a delicate tendon, 
runs along within the free marginal fold of the patagium of the 
wing, in common with the tendon of the tensor patagii longus, to 
blend with it just before reaching the carpal joint. 
I propose to call this muscle the dermo-tensor patagii, it being 
partially connected with the integumentary system of muscles in 
the birds in which 1 have thus far found it. 
Searching for it in all the other American Swallows, I find it 
to be about equally well developed in every species, and absent in 
none of them. 
This muscle surely does not correspond with the “ bicipital slip 
of the patagium,” as described by Gfarrod, and dwelt upon as the 
tensor patagii accessorius by Professor T. Jeffery Parker in his 
‘ Zootomy ’ (1884, p. 251) as occurring in the Common Pigeon, 
for it makes no connection whatever with the biceps muscle. 
Being desirous at this point of determining its presence or ab- 
sence in a few other groups of bitds, 1 stepped aside for the 
moment, and first examined a number of Passerine types, including 
very diverse forms, — it was present in all of them. Next, with 
the Caprimulgi, Trochili, and Cypseli, I found it completely ab- 
sent, as it was also in a specimen of Tyrannus tyrannus, kindly 
sent me by Mr. H. K. Coale of Chicago, from which 1 am led to 
inter that it does not occur in the mesomyocliau Passeres. 
Further than this I did not pursue the subject, but left it for 
subsequent investigation and the reseai ches of others interested 
in such matters *. 
Of the Pectoral Muscles. 
Every species of American Swallow has been dissected by 
me to ascertain the character and number of these important 
* Further opportunities for examining the literature of this subject now 
enable me to state that the muscle here described is the “pars propatagialis 
musculi cucullaris ” of Fiirbringer and Gadow ; and it has been carefully consi- 
dered by me in an extensive work upon the muscles of birds now in the hands of 
the Smithsonian Institution for publication. — E. W. S. 
