STUDIES or THE MACROCniRES. 



345 



evidently composed of two loDgitudiiial slips coming off from the 

 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 and 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 evideutly 

 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 longtis 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 

 radialis 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 Capi'imulgi 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 dilfer for the several genera very appreciably, and 

 on proceeding with my dissections of Antrostomus and CJior- 

 deiles I am the more convinced that, ns genera, they arc very 

 well-marked ones. 



Of the Fectoral Muscles. 



Both in Antrostomus and Chordeiles all three of the pectoral 

 muscles are present. Pectoralis major and pectoralis secundus 



