370 
DR. R. W. SHUEELDT’s MORPHOLOGICAL 
of his dissection of the parts in question, and it may he seen in 
figure 1, plate xxiv. of his ‘ Collected Scientific Memoirs.’ 
With the exception of leaving off the lower extensor of the 
forearm, his drawing is correct, and from it we see that the 
tensor patagii longus arises and is inserted pretty much as we 
find it in most birds ; hut with respect to the tensor patagii 
brevis a very marked departure is met with, for that muscle is 
as prominent as any other in the arm, more so than the majority 
of them. It may he said to he somewhat pear-shaped in form, 
with its larger end at the origin at the shoulder, while the smaller 
extremity becomes attached to a tendon which passes directly 
over the upper surface of the extensor metacarpi radialis Iongior , 
longitudinally. 
This tendon arises at the outer condyle of the humerus, and 
passes to the carpus for insertion, and is very well shown in 
Garrod’s drawing of Patagona. 
I find it present in all the Trochili, where, so far as I know, 
it constitutes a unique method of insertion for the tensor patagii 
brevis , and to make it clearer I present a drawing of it for 
TrocMlus platycercus (PI. XXII. fig. 28). 
Since Garrod saw so clearly this very unusual insertion of the 
tensor patagii brevis in the Humming-birds, I am surprised 
beyond measure that he did not at once make careful comparisons 
with the Cypseli in this particular ; had he done so, he would 
have found, as I have, that the mode of insertion of this muscle 
in those birds is entirely different. In the first place the body 
of the muscle is comparatively much smaller ; it is also of a very 
different form, being oblong and not pear-shaped ; finally it is not 
inserted into any special tendon , but directly upon a tendinous 
fascia on the surface of the extensor metacarpi radialis Iongior , 
and its fibres, becoming slightly tendinous, run dowu with that 
muscle for insertion at the external condyle of the humerus. 
In PI. XXII. fig. 29, I present a drawing made directly 
from my dissection of these parts in a specimen of Cheetura 
pelagica. 
As both the Humming-birds and Swifts have short humeri 
(though “shortness” is not a character, I believe) and have 
developed a large tensor patagii brevis (though “ size ” is not a 
character either, I believe) it might not unnaturally be expected 
that they should have this particular muscle short and thick ; 
but when we come to examine the true morphology, how vastly 
