280 SLENDER-BILLED GUILLEMOT. 



lower mandible 1 T %; wing from flexure 5 T \', tail 1-^; tarsus 4|; middle toe 

 |i, its claw ||. 



Two other individuals, apparently more advanced, or perhaps adults in 

 winter, have the upper parts brownish-black; the lower white but finely- 

 mottled, a small portion of the extremity of each feather being greyish- 

 dusky. The white bands on the hind neck and scapulars are formed, and 

 the lower surface of the wing is brownish-grey. 



FAMILY XLV.— COLYMBINiE. DIVERS AND GREBES. 



Bill of the length of the head, straight, rather stout, much compressed, 

 pointed; upper mandible with the dorsal line declinate, almost straight, or 

 towards the end convex; nasal groove rather long, feathered at the base. 

 Nostrils basal, linear, direct, pervious. Feet stout, short, placed extremely 

 far behind ; tarsus extremely compressed ; toes four, the first very small, and 

 lobed; the anterior united by webs, which in some are lobed. Plumage 

 dense, short, glossy, generally silky beneath. Wings small, very narrow, 

 acute. Tail very short, sometimes extremely small, and forming a slight 

 tuft. Tongue slender, trigonal, tapering; oesophagus very wide in its whole 

 length, or narrowed in the anterior part with the proventriculus wide; 

 stomach generally large, muscular, with a dense rugous epithelium; intestine 

 rather long and wide; as are the coeca; cloaca globular. 



