6io 



MUSCULAR SYSTEM 



leg ; but these four principal modifications are linked to each other 

 by intermediate stages, which moreover frequently occur in closely- 

 allied genera or even species. Thus the caudal head is very weak 

 in (Edicnemus su-percUiaris and (E. bistriatus and, as Garrod found, 

 does not exist in GB. grallarius. Dicholophus cristatus, like Otis, has 

 lost it, but D. burmeisteri the iliac head as well. In Ciconia, the 

 Striges and Catliartidw the whole muscle is represented only by the 

 feebly-developed caudal head, and in Leptoptilus this also is lost. 

 In some of the Limicolse, for instance Charadrius pluvialis and Vanellus 

 cristatus, the presence of the iliac head is an individual variation. 

 In Pedionomus the iliac head is very large, while the caudal is 

 reduced to a very thin and feeble slip that does not even reach the 

 femur, but merges into the iliac : if this reduction were continued 

 Pedionomus would agree with Pavo and Meleagris and not with 

 Turnix, in which the iliac head is absent. Thus the taxpnomic 

 value of this muscle may be judged from the following table, 

 shewing its four principal modifications : 



