364 



DK. B. W. SHUFELDt's MORPHOLOGICAL 



parisous of these parts as they occur in Micropus and Tachy- 

 cineta, and further on, wlieu we come to examine the skeleton of 

 Chcdtum^ a few more words on the subject may be added. 



Of the Skeleton of the Limhs in Swalloivs. — All of the Hirun- 

 dinidse agree with the true Passeres in having the little ossicle 

 known as the os humero-scapulare at the sboulder-joint, but I 

 have failed to find it in the Cypseline birds. 



In the Proc. Zool. Soc. for Ajjril 1887 I figured the humerus of 

 Tachycineta thalassina, and further on in this article I shall have 

 to refer to that drawing. Now, so far as the humeri of the other 

 Swallows are concerned, they all more or less resemble the bone 

 as found in Tachycineta : they are invariably non-pneumatic, 

 proportionately short in the shaft as compared with the size of 

 the bird, and quite so relatively when taken in comparison with 

 the Passeres generally. Especially in Chelidon is this brevity of 

 the humeral shaft noticeable ; and it becomes of interest to know 

 that in a specimen of this Swallow I find a humerus 15 millim. 

 long to an ulna 24 millim. long, and in Progne a humerus 

 22 millim. long to an ulna of 33 millim., while in a Swift 

 {Micropus) we have a humerus 11 millim. long to an ulna of 

 but 16 millim. in length, showing a diff"erence of 9, 11, and 

 5 millimetres respectively. 



Swallows have at least one good-sized sesamoid at the elbow, 

 but I thus far have failed to detect any such small bone in a 

 Swift; in Micropus, however, I find in the same tendon a small 

 nodule of dense cartilage. 



The shafts of both ulna and radius are noticeably straight for 

 nearly their entire lengths, and in their general conformation 

 depart but little from the usual form assumed by these bones in 

 the Passeres at large. 



I have already pointed out elsewhere that n a Swift {Micro- 

 pus) these bones are also markedly straight, and are, com- 

 paratively speaking, almost as short for a bird of its size as is the 

 humerus, — Swifts, as a rule, deriving their length of wing from 

 the long bones of the pinion, and not from those of the brachium 

 and antibrachium. 



Eadial and ulnar ossicles are found in the carpus of all 

 Hirundine birds, as usual, and in their form and method of articu- 

 lation no departure whatever is made from the composition of 

 the wrist-joint, as seen in all others of the group. 



There are no claws on the finger-end in the manus and 



