OitDER PYGOPODES. 



THE DIVING BIRDS. 



The Pygopodes include three very distinct families of birds, all of which are 

 well represented in North America. Some authors include in this Order the Pen- 

 guins {Sphcniscidw) ; but they possess so many peculiar features as unquestionably 

 to entitle them to the rank of a distinct Order {Sphcnisci). 



The families of Pygopodes which come within the scope of the present work may 

 be defined as follows : — 



A. Hallux present. 



1 . Podicipidae. Toes lobed, the nails flat, broad, and rounded at tips ; tail rudimentary ; a 



bare loral stripe extending from the bill to the eye ; bill variable in form, but always 

 more or less elongated. 



2. Urinatoridae. Toes fully webbed, the nails curved, acute, claw-like ; tail normal ; lores 



completely and compactly feathered ; bill elongated, acute, compi'essed. 

 D. IInUiix (ihscnt. 



3. Alcidae. Toes fully webbed, the claws curved and acute ; tail normal ; lores feathered ; 



bill excessively variable in form. 



FAMILY PODICIPID^. — The Grebes. 



Chak. Swimmers resembling the Loons in the posterior insertion of the legs, 

 but tlie toes lobate and semipalmate, instead of completely webbed, the claws 

 broad, flat, and nail-like, instead of normally narrow and curved. Bill variable 

 in shape ; nostrils variable, but witliout an overhanging lobe ; wings very short 

 and concave, the primaries covered by the secondaries in the closed wing ; tail 

 rudimentary, consisting of a mere tuft of downy, loose-webbed feathers, without 

 perfectly formed rectrices ; plumage of the lower surface remarkably silky and 

 lustrous, usually white. 



The Grebes have by many authors been included in a single genus — Pod'icejjs 

 (= Colp/ibus) — while a majority of writers admit but two — Podiceps and Podi- 

 /i/tnhus. The former, however, in this comprehensive sense, contains many extremely 

 dissimilar forms, and sliould, it appears to us, be subdivided, as has been done by 

 Dr. Coues in his monograph of the family (''Pr. Philad. Acad." 1862, p. 230). The 

 following North American genera a])pear to be rather well characterized. Colyvibus, 

 it may be remarked, approaches Mchmnplwrus through the South American C. major, 

 BoDD., a species having the bill of JEclinwpJiorus, but the coloration and shorter 

 neck of a true Colymhus. 



