134. UÚria (Guillemot). Bill strong, nearly straight, sharp-pointed, of moderate length; nostrils basal, partly covered by a feathered membrane; first primary longest.
135. Mérgulus. (Little Auk). Bill strong, conical, slightly curved, shorter than the head; nostrils basal, partly covered by a feathered membrane; first and second primaries equal.
136. Fratercula (Puffin). Bill shorter than head, higher than long, ridge of upper mandible higher than crown; both mandibles much curved throughout, transversely furrowed, notched at tip; nostrils basal, almost closed by a naked membrane.
FAMILY COLYMBIDÆ
(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 smaller than males.
137. Colymbus (Diver). Bill forming a pointed cylindrical cone; front toes entirely palmated; tail very short.