xxiv SYSTEMATIC ARRANGEMENT OF THE GENERA OF BIRDS 



SUB-FAMILY LARINM 

 BiU with upper mandible longer and bent over tip of under one. 



130. Larus (Gull). Bill moderate, strong, sharp-edged above, compressed, 



slightly decurved ; hind toe high on the tarsus ; first primary nearly 

 equal to the second, which is longest ; tail even, or but slightly 

 forked. Page 281 



131. RissA (Kittiwake). Bill rather short and stout, considerably decurved; 



hind toe minute and usually obsolete ; first primary slightly exceed- 

 ing second ; tail perceptibly forked in young, nearly square in adult. 



Page 287 



SUB.FAMILY STERCORARIINM 



Bill with a cere; claws large, strong, hooked. 



132. Stercorarius (Skua). Bill moderate, strong, rounded above, com- 



pressed towards the tip, which is decurved ; nostrils far forward, 

 diagonal, pervious ; hind toe very small, scarcely elevated ; the 

 middle tail-feathers more or less elongated. Page 288 



ORDER PYGOPODES 



Wings short 



FAMILY ALCID^ 



(Auks) 



BiU much flattened vertically (compressed) ; wings short ; legs placed at 

 the extremity of the body ; feet three-toed, palmated ; tail short. Food, 

 mostly fish, and captured by diving. 1 



133. Alca (Razorbill). Bill large, sharp-edged, the basal half featheredt 



the terminal part grooved laterally ; upper mandible much curved 

 towards the point ; nostrils nearly concealed by a feathered mem- 

 brane ; tail pointed. JPage 291 



134. Uria (Guillemot). BUI strong, nearly straight, sharp-pointed, of 



moderate length ; nostrils basal, partly covered by a feathered 

 membrane ; first primary longest. Page 292 



135. Mergulus. (Little Auk). BUI strong, conical, slightly curved, 



shorter than the head ; nostrils basal, partly covered by a feathered 

 membrane ; first and second primaries equal. Page 294 



136. Fratercula (Puffin). BiU shorter than head, higher than long, 



ridge of upper mandible higher than crown ; both mandibles much 

 curved throughout, transversely furrowed, notched at tip ; nostrUs 

 basal, almost closed by a naked membrane. Page 295 



FAMILY COLYMBID^ 



(Divers) 



Bill slightly compressed, not covered with a membranous skin ; edges of 

 the mandibles unarmed, or but slightly toothed ; wings short ; legs placed 

 far behind ; tarsi very much compressed ; toes four. Food, fish and other 

 aquatic animal substances obtained by diving. Females smsjler than males. 



137. CoLYMBUS (Diver). BiU forming a pointed cylindrical cone; front 



toes entirely palmated ; taU very short. Page 297 



