STUDIES OF THE MACROCHIRES. 
345 
evidently composed of two longitudinal slips coining off from tlie 
distal apex of the muscle together, they being but lightly held 
together, as they descend towards the muscles of the forearm, 
by a delicate connective tissue. The anterior or distal division 
of this double tendon is the one which becomes inserted in the 
extensor metacarpi radialis longior muscle of the forearm at the 
juncture of its tendon aud fleshy part. The inner slip of the 
main tendon of the tensor patagii brevis, or the slip next to 
the humerus, is directed as in the Caprimulgi generally. In other 
words, the arrangement here is the same, only the tendon of 
the muscle makes it appear somewhat different from the 
arrangement in the Whip-poor-will, upon dissection, from the 
fact that in the main tendon the two slips are so evidently 
distinct. Both of these birds possess the “ bicipital slip,” shown 
by Grarrod to be present in the Caprimulgi. 
There is yet another point, however, present in the Night- 
hawks which I have failed to find in the specimen of Antro- 
stomus before me. It is this : when the tendon of the tensor 
patagii longns muscle comes to be about opposite the points 
where the slips of the tendon of the tensor patagii brevis are 
inserted into the structures of the forearm, it sends off a delicate 
little tendinous slip which is inserted upon the extensor metacarpi 
raclialis longior muscle, at the same point where the distal slip 
of the tendon of the last-named muscle is also inserted, i. e. 
at the point of union of its tendon and corneous portion. 
On reading over this short description as detailed in the last 
few paragraphs, it seems hardly necessary to give any figures to 
make my remarks the clearer ; it will be well to note, however, 
that among the North-American Caprimulgi at least — and it 
will undoubtedly hold good for the entire group, — the method 
of insertion of the slips of the tendons of these patagial muscles 
of the arm may differ for the several genera very appreciably, and 
on proceeding with my dissections of Antrostomus and Chor- 
deiles I am the more convinced that, as genera , they are very 
well-marked ones. 
Of tlie Pectoral Muscles. 
Both in Antrostomus and Chordeiles all three of the pectoral 
muscles are present. Feet or alls major and pect oralis secundus 
