XXXVlll INTRODUCTION. 



Order PYGOPODES. 



Family ALCID.K. 



AiXA, IJniunis. — Bill straight, large, compressed, very much decurved towards 

 the point, basal half of both mandibles covered with feathers, grooved towards 

 the point, the superior mandible hooked, the under one forming with it a 

 salient angle. Nostrils lateral, marginal, linear, near the middle of the beak, 

 the aperture almost entirely closed by a membrane covered with feathers. 

 Wings short. Tail pointed. Legs short, very far back ; only three toes, all 

 in front, entirely webbed ; claws but slightly curved (p. 679). 



Uria, Brisson. — Bill of moderate length, strong, straight, pointed, compressed ; 

 upper mandible slightly curved near the point, with a small indentation or 

 notch in the edge on each side. Nostrils basal, lateral, concave, pierced 

 longitudinally, partly closed by membrane, which is also partly covered with 

 feathers. Wings short, first quill the longest. Tail shorter than in Alca. 

 Legs short, slender, placed behind the centre of gravity in the body ; feet 

 with only three toes, all in front, and entirely webbed (p. 683). 



Mergulus, Vieillot. — Bill shorter than the head, thick, broader than high at the 

 base ; culmen arched ; upper mandible indistinctly grooved, under man- 

 dible with the symphysis very short and oblique, the tips of both notched ; 

 commissure arched. Nostrils lateral, round, situated at the base of the bill, 

 and partly covered with small feathers. Wings and tail short. Legs far 

 back, short ; feet with three toes, all directed forwards and united by a mem- 

 brane (p. 689). 



Fratercula, BHsson. — Bill higher than long, much compressed ; both mandibles 

 arched, transversely grooved, notched towards the point. Nostrils lateral, 

 naked, almost entirely closed by a membrane. Wings and tail short. Legs 

 very far back ; feet with three toes only, all in front and fully webbed ; claws 

 curved (p. 691). 



Family COLYMBIDyE. 



COLYMBUS, Linntrus. — Bill about as long as the head ; strong, straight, rather 

 compressed, pointed. Nostrils basal, lateral, linear, perforate. Wings 

 short, the first quill the longest. Tail short and rounded. Legs thin, the 

 tarsi compressed, placed very far backwards, and closely attached to the 

 posterior part of the body ; toes three in front united by membranes, one 

 toe behind with a small membrane, articulated upon the tarsus ; the claws 

 flat (p. 693). 



Family PODICIPEDID^. 



PoDiciPES, Latham. — Bill of moderate length, straight, hard, slightly com- 

 pressed, pointed, forming an elongated cone. Nostrils lateral, concave, 

 oblong, open in front and perforate, closed behind by a membrane. No true 

 tail. Wings short, first three primaries nearly equal, and the longest in the 

 wing. Legs and feet long, attached behind the centre of gravity ; tarsi very 

 much compressed ; three toes in front, one behind ; anterior toes veiy much 

 flattened, united at the base, surrounded by a lobated membrane ; hind toe 

 also flattened, articulated on the inner surface of the tarsus ; claws large, 

 flat (p. 701). 



