1890.] ANATOMY OF PODICA SENEGALENSIS. 427 



there is a distinct division of the pectoral tract such as occurs in the 

 Rails. The inner branch is much broader than the outer, and ends 

 abrupt!}', as figured by Nitzsch in Rallus aquaticus, a short waj' 

 below the wing ; the inner branch of the pectoral tract is if anything 

 rather broader nearer to its free extremity than at its origin ; it ia 

 1^ inches long ; the outer branch of the pectoral tract is wider at 

 first, though not so wide as the inner branch. The humeral tracts 

 are very strong, and certainly more than two feathers wide (2-6). 

 In almost every point, therefore, the pterylosis of Poclica senega- 

 lensis difl'ers from that of its American ally. 



As regards other external characters, I find that there is a close 

 agreement between the Neotropical and African forms. 



The oil-gland is distinctly tufted. 



The contour-feathers have no aftershaft. 



There are 18 rectrices. 



I count 21 remiges. 



It is important to notice that the 5th cubital remex is not wanting 

 [see Wray, 10 ; Sclater, 9]. 



The pterylosis of Fodica is so difi'erent from that of Ueliornis, that 

 we must assume one of two things : either that Nitzsch's description 

 is wrong, or that the pterylosis — at least in this group — has not the 

 significance that is frequently attached to it. 



As a mere question of probability, it does not appear to me to be 

 necessary to pin our faith too firmly to the data of pterylography. 

 And I should be dis;posed to regard Nitzsch's description of HeUornis 

 as likely to be right. 



§ 2. Myology \ 



The pectoralis j^rtmus muscle is separable into two layers, which 

 are even to be distinguished by a slight difference of colour ; the 

 sepa.ration is effected by a tendinous sheet. The muscle arises from 

 the keel of the sternum and from its outer margin behind the third 

 pectoral and alongside of the second pectoral, and from the hinder 

 part of the sternum which is not reached by the second pectoral ; 

 it has also an origin along a line running parallel to but of course 

 below the uncinate processes from the ribs^ 



Pectoralis secundus: this muscle is large and extends nearly to 

 the end of the sternum ; it has the usual bipinnate form. 



The seapulo-humeralis is a broadish band of muscle underlying 

 the tendon of the bicejjs. 



In the accompanying sketch (Plate XXXIX. fig. 1) is illustrated 

 the patagial muscles of the bird. 



^ I have in this section principally confined myself to those muscles whir^h 

 are known to be of use for systematic purposes. 



^ Fiirbi-inger [i, p. 417 and note] denies that this extrasternal portion of 

 the pectoral muscle springs from the ribs ; it takes its origin, according to biiii, 

 from the " parasternal fascia " which covers the steiMio-costal muscles. 

 Nevertheless I cannot but think that in Poclica senrffalcnsis the origin is actually 

 in part from the ribs themselves. 



