Contributions to Bird- Anatomy and Classification. 17 



of describing and figuring their arrangement in these birds 

 was never carried out. In hisMSS. and drawings^ however, 

 he has recorded their condition in very many groups. 



VII. Certain other Muscles. 

 In his paper on Chauna [supra, p. 11) , Prof. Garrod, for 

 the first timCj called attention to the value in classification 

 of certain other myological facts. These are : — 



(1) The presence or absence of the " expansor secundari- 

 orum " muscle. 



This is a slender muscle which arises from the last few 

 (generally two or three) secondary quills and has a pecu- 

 liarly long and slender tendon, which, running superficially 

 posterior to the humerus, together with the axillary vessels and 

 nerves, is inserted into the thorax in different ways in different 

 birds. One common arrangement is that found well developed 

 in the Storks, and hence called ^^ ciconiiform." Here the 

 proximal part of the tendon is T-shaped, it splitting into two 

 parts, one being inserted into the coracoid near the junction 

 of this bone with the sternum, the other into the scapula close 

 to the coraco-scapular articulation. In other cases the tendon 

 may end hy joining the coraco-brachialis brevis muscle, so as 

 to appear to be part of that muscle, as in the Fowl and most 

 of the Gallinaceous birds ; or the tendons of the two sides may 

 join in the middle line, as in most of the Anseres ; or other 

 and more complicated arrangements, duly described in the 

 paper above referred to, may obtain. The only Anomalogo- 

 natous birds in which this muscle is present are the Coraciidse. 

 A table (/. c. p. 199) records the nature of this muscle in the 

 families of Homalogonatous birds. In many it is quite absent. 



(2) The presence or absence of a biceps slip to the patagium 

 of the wing. 



In many birds there is given off from the anterior margin 

 of the biceps muscle of the arm a distinct and most peculiar 

 muscular slip, Avhich joins the patagial membrane of the 

 wing. Its presence or absence is a very constant character 

 amongst closely allied birds. 



(3) The area of origin of the obturator internus musch.:. 

 SER. IV. — VOL. v. c 



