14 



that this sequence of gesera cannot be broken in upon to any considerable 

 degree, without the rupture of a natural series as a consequence. 



Family ALCIDJS. 

 Ch. — Tridactylous, brachypterous, brachyurous Natatores, with lateral 

 nostrils. 



A. — Subfamily Alcin.^. — Not crested; with feathered nostrils; compressed 

 cultriform bill, much higher than wide at base, without appendages, but 

 grooved on the sides ; tail pointed. 



1. Alca, — Wings rudimental, not admitting of flight. 



2. Utamania. — Wings fully developed, admitting of flight. 



B. — Subfamily Phaleridin.e. — Usually crested, or with elongated feathers 

 on head ; with naked nostrils ; bill variable, always compressed, higher than 

 wide at the base, often with appendages ; tail nearly even. 



3. Fratercula. — Inner lateral claw' very large, semi-circular, acute, hori- 

 zontal; bill excessively thin, its base ridged, its culmen simple, with one 

 curve; under mandible grooved ; no crest; palpebral appendages ; a furrow 

 in plumage behind eyes ; tarsi anteriorly scutellate. 



4. Lunda. — As in Fratercula ; culmen with an accessory piece, and two 

 curves ; under mandible smooth ; long crests ; no furrow in plumage ; no 

 palpebral appendages. 



5. Ceratorhyncha. — Inner lateral claw normal ; bill without a basal rim ; 

 base of upper mandible with a prominent upright horn ; rami of lower man- 

 dible with an accessory piece ; head with elongated feathers ; tarsus ante- 

 riorly scutellate. 



6. Sagmatorrhina. — Base of upper mandible overlapped by a soft mem- 

 brane ; no accessory piece on lower mandible ; otherwise as in Ceratorhyncha. 



7. Simorhynchus. — Bill variable, usually with irregular outline or with 

 appendages ; head with a crest or elongate feathers ; tarsi reticulate. 



8. Ptychorhamphus. — Bill stout, conico-elongate, wide at base, acute at tip; 

 base of upper mandible with ti'ansverse stride ; upper border of nostrils 

 dilated, flaring ; no crests. 



C. — Subfamily Urin/E. — Nostrils more or less completely feathered; bill 

 elongated, more or less slender and subulate, without appendages or vertical 

 grooves; head not cresied, (except in one species.) 



9. Mergulus. — Nostrils nearly circular, not completely feathered ; bill 

 stoutest and shortest in this section ; tail much graduated; tarsi scarcely 

 compressed, anteriorly broadly scutellate. 



10. Synthliborharnphus. — Nostrils broadly oval, incompletely feathered ; bill 

 stoutish, but much compressed ; tail nearly even ; tarsi excessively com- 

 pressed, anteriorly and internally scutellate. 



11. Brachyrhamphus. — Nostrils oval, feathered; bill small, very slender; 

 tail short, little graduated ; tarsi reticulate, very small and slender, not 

 compressed, 



12. Uria. — Bill about equal to tarsus ; gonys half the culmen ; nasal fossfe 

 wide aud deep, not entirely filled with feathers ; upper mandible with no 

 groove at tip ; outer lateral claw grooved ; tail contained 2^ times in the 

 wing ; tarsi reticulate ; no furrow in plumage of head. 



13. Lomvia. — Bill much longer than tarsus ; gonys much more than half 

 the culmen ; nasal fossae long and narrow, completely feathered ; upper 

 mandible with a groove at tip ; outer lateral claw smooth ; tail contained 

 3f times in wing; tarsi anteriorly scutellate; a furrow in plumage behind 

 the eyes. 



