in the Classificution of Birds. v 
lished description, and one the importance of which Garrod, 
even if he knew of its existence, certainly overlooked. 
When present, its chief carneous portion occurs in the free 
marginal fold of that triangular. duplicature of the common 
integuments found between the root of the neck and the 
tip of the shoulder in birds. It first came to my notice in a 
specimen of Progne subis, whereupon I at once dissected a 
number of other individuals of the same species; and I 
found it equally well developed in all of them. 
This muscle, in part, is a dermal muscle, and arises from 
the integuments on the anterior aspect of the neck at about 
its lower third ; at its origin its fibres spread out fan fash- 
ion, their terminal fibres meeting those of the muscle of 
the opposite side in the median line. Here it is quite ad- 
herent 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 ten- 
don, runs along within the free marginal fold of the pata- 
gium of the wing, in common with the tendon of the ten- 
sor patagii longus, to blend with it just before arriving at 
the carpal joint. 
Garrod chose the wing of Icterus vulgaris to illustrate the 
arrangement of the patagial muscles in the Passeres, and 
in his figure of it, a tendinal slip is shown cut short, of 
which he says nothing, but which evidently belongs to this 
muscle. Nowhere else is this shown or alluded to in his 
work.* 
I propose to call this muscle the ‘dermo-tensor patagii,’ 
it being partially connected with the integumentary system 
of muscles in the birds wherein I have thus far found it. 
Upon dissection, I find it present in each and all of the 
other United States Hirundinidae ; in all true passerine 
birds, including Ampelis ; but absent in the Caprimulgi, in 
the Trochili, in the Cypseli, and, if we may judge for all 
the typical Passeres mesomyodi from the condition in Tyr- 
annus tyrannus, it is also wholly absent in them. Further 
than this, I have not investigated the matter, but it will be 
*Plate 21, fig. 2, of his Coll., Sci. Mem., and Fig. 1, of the present paper, 
