NATURAL SCIENCES OF PHILADELPHIA. 



33 



Fig. 5. — S. SucTileyi, Juv. Nat. size. 

 Fig. 4.-5. Suckleyi, Adult. Nat. size. Cassin's type specimen. 



No vestige of a horn at base of upper mandible ; this being covered with a 

 soft skin, overlapping the culmen, extending to the nostrils, which open be- 

 neath its lower border. That part of the bill occupied by tlie membraue is 

 depressed below the level of the rest, both on the ridge and sides. The mem- 

 brane is shrunken and shrivelled in its present state. There appears to have 

 been a slight tumidity, in the fresh state, of this membrane, just on the ridge, 

 which may have elevated it to the level of the rest of the culmen, and which 

 could possibly even have been inadvertently called a '' knob " by one who re- 

 garded it as the beginning of a horn. No trace of an intercalated piece be- 

 tween the mandibular rami, which have thin, sharp, smooth edges, and come 

 together in a fine point at the symphysis. Bill much smaller, weaker, and 

 particularly less deep at the base than that of C. monocerata ; but not much 

 shorter, nor comparatively even so much compressed as in the latter bird. 

 Culmen regularly decurved from base to tip ; the latter moderately overhang- 

 ing ; rictus at first nearly straight, then gently declinate ; gonys nearly straight, 

 slightly concave ; outline of mandibular rami about straight. 



Decidedly smaller than monocerata ; the wing comparatively longer. Length 

 about 14-00 ; " extent 25-50," (label) ; wing 7-25 ; tarsus 1-10 ; middle toe and 

 claw 1-90, outer do. 1-80, inner do. 1-45; bill: chord of culmen 1-30, of which 

 the membranous part is -30 ; rictus 1-85 ; gonys .75 ; depth of bill at base -60 ; 

 its width at same point -45. 



Young. (No. 4579, Mus. Smiths. Fort Steilacoom, W. T. Jan. 8, 1856. 

 Dr. G. Suckley. Mr. Cassin's type of the species, as described I. c.) " Membrane 

 at base of upper mandible grayish dusky black ; middle of both mandibles 

 dingy orange, their tips dusky ; iris pale hazel ; under surface of the webs of 

 the feet, and the posterior aspect of the tarsi dusky black; upper surface of 

 the toes bluish white, darker about the articulations ; nails black." (Suckley, 

 1. c.) The colors of the plumage are precisely as described for the }'oung C. 

 monocerata ; possibly a shade darker, with rather more white on the under parts 

 than in the corresponding age of the other species. 



Much smaller than the adult ; length " about 12.50; extent 24.00;" (Suck- 

 ley, 1. c.) : wing 6-50 ; tail 2-00 ; tarsi 1-00 ; bill along culmen 1-20, of which 

 the membranous portion is -30; along rictus 1-60; along gonys -60; its depth 

 at base -40. The bill is small and slender; its general shape calls to mind the 

 bill of a young gull of one of the smaller species. The several outlines, par- 

 ticularly that of the culmen, are straighter than in the adult; the tip is less 

 decurved. The bill is much longer, relatively and absolutely, than that of the 

 corresponding age of monocerata ; it is comparatively more slender. There is 

 no trace of a knob ;* the membrane has precisely the same characteristics as 



• Dr. Suckley (1. c), speaking of this specimen, uses the word "knob" in connection 

 with it. His expression is to be taken as indicating merely the turgidity of the soft 

 membrane during the life of the bird ; which raises the membrane to or above the level 

 of the rest of the culmen. The membrane, being very soft, shrinks and shrivels in dry- 

 ing, and the prominence disappears. 



1868.] 3 



