278 
AVES. 
from its base ; edges of both mandibles widened at their base, 
compressed, and serrated, from thence to the tip; under mandi¬ 
ble slightly curved, on its lower margin three-fourths its length, 
and acutely tapering to the point; nostrils near the base, lateral, 
pervious, and partly concealed by a membrane; legs very 
short, strong, placed far back; three anterior toes, connected to 
their tips by a membrane; the hallux small, short, placed be¬ 
hind, and free ; wings long, first and second quills longest ; 
tail short, but having two long filamentous central feathers, 
which are slightly forked. 
Phaeton phcenicurus. — The Red-Tailed Tropic Bird. 
Plate LV. fig-. 4. 
Plumage white, with a delicate rosy tinge ; three longest se¬ 
condary quills clouded with black; upper auricles and sinciput 
with a few crescent-shaped brown spots; a black line over the 
eyes, and a patch of the same betwixt the bill and eye; bill and 
middle tail feathers scarlet; legs gray. Two feet ten inches 
long to the point of the tail. Inhabits the South Seas. 
Genus 21.—COLYMBUS.— Latham. 
Generic Character. —Bill as long as the head, strong, com¬ 
pressed, acutely pointed, and somewhat cylindrical ; upper 
mandible longer than the under one; nostrils situated at the 
base of the bill, concave, and half-closed by a membrane; legs 
placed far behind ; tarsus strong, compressed; three anterior toes 
very long, united to their tips by a web; hallux short, articulated 
interiorly, united by a rudimentary membrane ; wings of medium 
length ; the third quill the longest; tail very short and rounded. 
Colymbus glacialis. — The Great Northern Diver. 
Plate LXVII. fig. 3. 
Head, throat, neck, back, and wings, deep iridescent black, 
with green and purple reflections ; throat with two white rings, 
longitudinally streaked with black lines; back and wings speckled 
with oblong spots of white; under parts white ; bill and legs 
black. Twenty-nine inches long. Inhabits the Arctic Seas. 
Genus 22.—URIA.— Brisson. 
Generic Character. —Bill of medium size, short in some species, 
straight, pointed, and compressed • upper mandible slightly bent 
