232 PROCEEDINGS OP THE ACADEMY OF 



the head, shorter than the tarsus. Length about 19 inches, wing 7*60. Bill 

 above 1-90, along gape 2-40, height at nostril -55. Tarsus 2-10; middle toe 

 and claw 2 - 65. 



Habitat. North America, generally. 



The present species has by most authors been considered identical with the 

 P. griseigena Bodd. (rubricollis of Latham,) of Europe. The differences, how- 

 ever, as pointed out by Reinhardt, are quite tangible, and so constant as to 

 render it very probable that they are of specific value. In the European bird 

 the bill measures 1-50 along the culmen, 2-00 along the gape, and -50 in 

 height at the nostrils ; the wing less than 7 inches. (See diagnosis for compari- 

 son). In color, too, the bills differ. In P. griseigena the extreme base of the 

 under mandible only is yellow, the color extending a little on the cutting edge 

 of the upper mandible at base. In Holbulli nearly the whole of the under 

 mandible, and the cutting edge of the upper, are yellow. 



Genus III. Sylbeocyclus Bon. 



Podiceps, Kaup, 1829, nee Lath. 



Sylbeocyclus, Bonaparte, 1832. (Typus Pod. minor, fide G. R. Gray.) 



Tachybaptes, Reichenbach, 1851. (Typus idem.) 



Gen. Char. Bill very short, much less than the head, scarcely more than 

 half the tarsus ; very stout, little compressed, the tip obtuse ; lateral outlines 

 about straight ; culmen a little concave at the nostrils, convex throughout 

 the rest of its length ; gonys straight to the angle, and from angle to tip ; the 

 former well defined. Wings short ; attenuation of primaries considerable ; 

 abrupt on the inner web. Tarsus stout for this family, much abbreviated, 

 scarcely more than three-fourths the middle toe and claw. Outer lateral toe 

 abou tequal to the middle. Size small ; body full ; neck short ; without de- 

 cided crests or ruffs. 



1. Sylbeocyclus dominicus (Linn.) 



Podiceps dominicus, Linn., 1766. Sylbeocyclus dominicus, ? 



Sp. Char. Adult. Without decided crests, but indications of them in the 

 length and fulness of the feathers of the parts. Crown and occiput deep 

 glossy steel blue. Sides of head, and neck all round dark ashy gray, deepest 

 behind, where it is tinged with bluish. Chin variegated with ashy and white. 

 Upper parts generally brownish black, with glossy greenish reflections. Pri- 

 maries chocolate brown, the greater portions of the inner vanes of all. the 

 whole of the four or five inner, except just at tip, together with the second- 

 aries, pure white. Under parts silky white, thickly mottled with brownish 

 dusky ; the abdomen uniform dusky gray. Upper mandible dusky, the lower 

 mostly yellowish. 



Dimensions. Length 9 - 50 ; wing 3*60; bill above *70 ; along gape 1*00 ; 

 tarsus 1*25 ; middle toe 1-75. 



Habitat. Central America ; Mexico ; Antillean Is. ; Gulf of California (Gam- 

 bel) ; Rio Grande (eggs in Smiths. Coll.). 



[Note. Sylbeocyclus minor , the type of the genus, is given by Nuttall as an 

 inhabitant of North America ; but its existence in this country is very doubt- 

 ful.] 



Subfamily PODILYMBINiE. 



Char. Bill exceedingly stout. Commissure abruptly decurved at the end. 

 Nostrils broadly oval. Bare loral space broad. Feathers of the forehead with 

 their shafts prolonged into stiff bristles. Tarsus not three-fourths the middle 

 toe. Toes connected at base for a considerable distance ; the lobe of the hind 

 toe moderate. Without decided crests or ruffs. 



Genus IV. Podilymbus Lesson. 



Podilymbus, Lesson, 1831. (Typus Colymbus podiceps, Linn.) 



Hydroka, Nuttall, 1834. 



Dasyptilus, Swainson, 1837, fide G. R. Gray. 



[April, 



