164 
Genus I.— C OLYMPUS, Linn. DIVER. 
Bill as long as the head, straight, rather stout, much compressed, taper- 
ing, pointed ; upper mandible with the dorsal line descending, and slightly 
convex towards the end, the ridge convex, narrowed towards the point, the 
sides nearly erect, convex, the edges sharp and considerably inflected ; the 
tip narrow ; nasal groove rather long, feathered at the base. Nostrils basal, 
linear, direct, pervious ; lower mandible with the angle extremely narrow 
and extending beyond the middle, the dorsal line straight and sloping 
towards the point, the ridge convex and narrow, the edges sharp and 
involute, the tip attenuated. Head of moderate size or rather large, oblong, 
narrowed before ; neck rather long and thick ; body elongated, much 
depressed. 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 scales ; toes four, hind toe 
extremely small, connected with the second by a very small membrane ; 
anterior toes united by entire membranes, the outer longest, the third a little 
shorter, all scutellate. Claws very small, depressed, blunt. Plumage short 
and dense, the feathers in general oblong. Wings very small and narrow, 
curved, first quill longest, secondaries broad and rounded. Tail extremely 
short, rounded, of more than twelve feathers. Tongue long, trigonal, taper- 
ing ; oesophagus very wide ; proventriculus extremely dilated ; stomach rather 
large, roundish, a little compressed, moderately muscular, with a rather 
thick, dense, longitudinally rugous epithelium ; intestine rather long and 
wide ; coeca rather long and wide ; cloaca globular. 
