COLYMBUS. 439 
Order PYGOPODES. 
For the characters of this order we cannot do better than quote the definitions given 
in vol. xxvi. of the ‘Catalogue of Birds’ :— | 
“Skull holorhinal and schizognathous; nares pervious; vomer cleft posteriorly 
for about } or 3 its length; basipterygoid processes absent : lachrymal not 
extending downwards to join the quadrato-jugal bar; quadrate with an elongate 
orbital process ; maxillo-palatine processes laminate, not rod-shaped ; dentary suture 
of mandible more or less completely obliterated; angulare truncate posteriorly ; 
furculum without a facet for articulation with the acro-coracoid ; pre-ilia not rising up 
to meet in the middle line above the fused neural spines of the synsacrum; post-ilia 
much longer than the pre-ilia and vertically compressed ; tibio-tarsus with the cnemial 
crest produced upward far beyond the articular surface of the femur; tarso-metatarsus 
laterally compressed; outer toe longest. Rhamphotheca simple. Nestling nidifugous.” 
The Order contains two Families—the Divers and the Grebes. 
Fam. COLYMBIDZ. 
The Divers have the hallux on a level with the fore toes, the latter being united by 
a web; the tail is composed of eighteen or twenty short stiff feathers (cf. Grant, 
Cat. Birds Brit. Mus. xxvi. p. 485). The family consists of a single genus, Cols ymbus. 
| COLYMBUS. 
Colymbus, Linn. Syst. Nat. i. p. 220 (1766) ; Grant, Cat. Birds Brit. Mus. xxvi. p. 486 (1898). 
American ornithologists employ the name Urinator of Cuvier for Colymbus of 
Linneus, 1766, holding that, in the 1758 edition, Linneus used Urinator for the 
Grebes, We prefer, however, to adhere to the Stricklandian Code and to recognize 
the genera of the 1766 edition. . 
Five species of Colymbus are known, all of them breeding far north in both 
hemispheres, and migrating southward in winter. 
1. Colymbus glacialis. 
Le Grand Plongeon, Brisson, Orn. vi. p. 105, t. 10. fig. 1*. 
Colymbus glaciulis, Linn. Syst. Nat. i. p. 2217; Grant, Cat. Birds Brit. Mus. xxvi. p. 495°. 
Urinator immer (Briinn.), Baird, Brewer, & Ridgway, Water-Birds N. Amer. ii. p. 446 *. 
Urinator imber (Gunn.), A. O. U. Check-l. N. Amer. Birds, p. 75°; 2nd ed. p. 3°; Herrera, 
La Nat. (2) i. pp. 1887, 330°. 
Pil. htem, Supra nigricans, plumis grisescenti-schistaceo late marginatis, pileo et collo postico concoloribus 
nigricantibus, nitore viridi inconspicuo, dorso postico et uropygio brunnescentioribus ; corpore tote 
