469 



GULLS AND ALLIED SPECIES. 



There are differences of opinion as to the species of Mer- 

 satores that ought to be included in the group of which the 

 genus Larus is to be taken as the type, some including in it 

 the Terns and Petrels, others considering these latter as 

 forming two families equivalent to that of the Gulls. As 

 usual in such cases " a great deal might be said on both sides 

 of the question." In the present state of ornithology it is 

 not of great importance, there being no criterion for distin- 

 guishing groups of any kind, — ordinal, or sub-ordinal. In 

 this family I include all birds that present the following 

 characters : — 



Body more or less compact, generally light ; neck of 

 moderate length ; head ovate, of ordinary size. Bill gene- 

 rally shorter than the head, straight, compressed, somewhat 

 declinate at the end ; upper mandible with the ridge convex, 

 the nasal groove rather long, the edges sharp and direct, the 

 tip declinate, rather acute ; lower mandible Avith the angle 

 long and very narrow, an angular prominence at the com- 

 mencement of the dorsal line, which is more or less concave 

 and ascending. Mouth of moderate width, opening to 

 beneath the eyes ; palate flat, with two prominent ridges, 

 and four series of reversed papilla?. Tongue fleshy, papillate 

 at the base, rather narrow, tapering to a narrowly rounded 

 point, and horny beneath. (Esophagus very wide ; proven- 

 triculus dilated ; stomach rather small, elliptical, moderately 

 muscular, with large radiated tendons, and very dense, thick, 

 longitudinally ridged epithelium ; intestine rather long, nar- 

 row ; coeca very small, cylindrical. 



