

304 THE RED-THROATED DIVER. 



Adult Male in summer. 



Bill as long as the head, slender but strong, straight, rather compressed, 

 tapering to a point. Upper mandible with the dorsal line almost straight, 

 the ridge convex, as are the sides, the edges sharp and involute; nasal groove 

 basal, short; nostrils basal, lateral, direct, oblong, pervious. Lower mandi- 

 ble with the angle extremely narrow and extending beyond the middle, the 

 dorsal line straight and sloping upwards to the point, the ridge convex, but 

 narrower than that of the upper mandible, the edges sharp and involute; the 

 point of both mandibles rather sharp. 



Head of moderate size, oblong, narrowed before. Neck rather long and 

 slender. Eyes rather small. Body elongated, somewhat depressed. Wings 

 small. Feet short, rather large, placed very far back; tibia almost entirely 

 concealed; tarsus short, exceedingly compressed, sharp-edged before and 

 behind, covered all over with reticulated angular scales; hind toe extremely 

 small, connected with the second by a very small membrane; the anterior 

 toes united by reticulated membranes, the fourth longest, the third a little 

 shorter, the second considerably shorter than the third; all covered anteriorly 

 with very narrow transverse scutella, the second toe with a free two-lobed 

 membrane; claws very small, depressed, rounded. 



Plumage short and dense; of the head and neck very short, blended; of 

 the lower parts blended, short, and with a silky gloss; of the upper slightly 

 glossed and somewhat compact; the feathers in general oblong and rounded. 

 Wings proportionally very small and narrow, curved; primaries strong, 

 tapering, first longest, second almost as long, the rest rapidly graduated; 

 secondaries broad, rounded. Tail extremely short, rounded, of twenty 

 rounded feathers. 



Bill bluish-black. Iris deep bright red. Feet brownish-black, the anterior 

 edge of the tarsus, the upper surface of the toes, the claws, and part of the 

 webs, pale livid flesh-colour. Fore part and sides of the head, throat, and 

 sides of the neck, of a fine bluish-grey; fore part of the neck rich brownish- 

 red; hind part of the head and hind neck longitudinally streaked with 

 greenish-black and pure white, each feather black in the middle, with the 

 sides white, the colours disposed in lines. The upper surface brownish- 

 black, tinged with green, more or less mottled with white according to age, 

 excepting the primary quills and the tail-feathers, the latter of which are 

 merely paler at the end. The whole under surface pure white, excepting 

 the feathers on the sides under the wings, some of those about the vent, and 

 the lower tail-coverts, which are greyish-brown, with w 7 hite margins and tips. 



Length to end of tail 25^ inches, to end of claws 27; extent of wings 

 43 T y, bill 2^; gap 3§; tarsus 3; fourth toe and claw 3|; wing from flexure 

 llf; tail 3. Weight 4 lbs. 



