346 STRUCTURE AND CLASSIFICATION OF BIRDS 



the other members of the genus, has the formula BXY + . 

 The ptcrijlosis is as in the Charadriidae, but the number of 

 rectrices may be as numerous as fourteen. There is no 

 liallux. In the skull the absence of basipterygoid processes 

 (sometimes indications of them are present, according to 

 GADOW) and the holorhinal character of the nostrils distin- 

 guish this family from the Charadriidae. The depressions 

 for the supra-orbital glands are well marked. The lacrymal 

 bones are nearly (occasionally quite, though by suture) 

 united with a process of the frontals, and form a canal, 

 through which the gland apparently passes ; this is seen in a 

 more exaggerated way in Chionis and in Vanellus (v. de- 

 scription of Chionididae) . The post-orbital angle is not 

 distinct from the post-frontal process. There are no occipi- 

 tal foramina, as in Charadriidae. There are sixteen cervical 

 vertebra, the last three of which have ribs of progressively 

 increasing length ; five or six ribs articulate with sternum. 

 Contrary to what is found in the Charadriidse, the coracoids 

 slightly overlap at their external articulation. 



Some of the visceral characters have been already dealt 

 with above in the general description of the Limicolse. 



There is a tendency for the ambiens not to cross the knee ; 

 this occurs individually with specimens of several species. 



The syrinx has not, except as an occasional variation, 

 any intrinsic muscles. 



(Edicneinus bistriatiis has on the anterior wall of the 

 cloaca two hardly elevated ridges, which end by slightly free 

 points, and seem to represent a rudimentary penis. 



The surgeon birds and ja9anas of the tropical regions of 

 the Old and New Worlds, with their enormously elongated 

 feet and their somewhat rail-like aspect, are now known to 

 belong to the Limicolae (and not to the Ralli), of which they 

 may be regarded as forming a distinct family, Parridae. 

 Their anatomy has been chiefly studied by FORBES.' As 

 with the Thinocoridae so with the present family there is a 

 character of the alimentary canal which immediately distin- 



1 ' Notes on the Anatomy of the Ja^anas,' P. Z. S. 1881, p. G39. 



