68 SATURAL II I SI on Y OF BinUS. 



World by sovcral uoograpliieal variations. The AiiuTii-an jj;ciiiis, Podilymhus, is par- 

 ticulailv cliarai-terized liy its liigli ami stout bill, ami \i\ tlii> bristly fi-athers of the 

 forehead. The American dab-chick, P. podiceps, is common in eastern North America. 



AVe have here to consider a small ijroup of binls, consisting of perliaps not wore 

 than four s])ecies, and constituting a separate suiierfamily wliicii we have called IIELI- 

 ORNrniOIDEJ2, though by no means convinced that this is the best ])lace that could 

 be assigned to them. They are more usually referred to the neighborhood of the rails, 

 but as this ]iositi-n does not satisfy us better, the view of the late Professor W. A. 

 Forbes has hero been followed in ])lacing them nearer to tlie grebes. 



With the latter, the tin-foots, or sun-grebes, as they liave also been called, agree in 

 the form of the bill, an<l like them they have lobated toes, whicli, among other things, 

 however, differ in liaving the middle toe decidedly longer than the outer one. Their 

 plumage is not dense and glossy like that of the grebes, from which the tin-foots differ 

 most essentially in having not less than eighteen well-developed tail-feathers. Another 

 ])oint characteristic of the ]iterylosis of these remarkable birds is that the featliers 

 are without an aftershaft. The head is small, and the neck very thin and narrow. 



The fin-foots are still a great puzzle to ornithologists, for not only is their structure 

 imperfectly known, but information concerning their habits is extremely .scanty. 

 Their geograj)liieal distribution is not less peri)lexing; for one genus, with one species, 

 JleUomis fulica, inhabits .South America, two species of the genus Podlca are peculiar 

 to Africa, while a third one is at home in eastern Asia, a distribution which offers cer- 

 tain ))oints of analogy to that of the darters. 



The South American tin-foot inhabits rivers of the Brazilian empire and other 

 eastern states on the Xeotrojiical continent. It is about the size of the European dab- 

 chick, of a brownish olive color above, with head and upper neck black ; it is buffy 

 white underne.Tth ; neck, throat, and a jiost ocular stripe )nire white. Very characteris- 

 tic are the broad and distinct black bands which cross the joints of the yellow feet. 

 The 'picapare,' as it is called by the inhabitants, prefere shadowy Mini (|uiet rivei-s, 

 even those of the deep virgin forests, feeding upon fishes, water insects, and seeds. It 

 is said to sit for hours on a branch overhanging the water and half submerged, but 

 diving is only resorted to in danger or when wounded. Two naked young ones are 

 hatched in Decendter. Heard from a distance, the voice is said to resemble the bark- 

 ing of a small dog. 



Tlie following superfamily, the ALCOIDEyE, is of a very varied appearance, and is 

 in many respects of great im|iortance, not only on account of the great number of differ- 

 ing forms of which it is coin])Osed, and the zoological interest connected with them, 

 but also because the enormous number of individuals of several s]K'ci;s make them a 

 notable object in the economy of many a tribe of mankind inhabiting the inhospitaljle 

 regions surrounding the north pole. In fact, the members of this supcrfnmily are dis- 

 tinctive of the northern circumpolar fauna, and not a single one is found on the 

 southern hemisphere, nor does a single species inlial)it any part of the tropical zone. 

 As a consequence of the circumpolar distribution, all the genera and nearly all the 

 species occur in America. 



We distinguish two very well defined families, the Urinatoridaj an<l the Alcidae. 

 Externally they differ especially by the former having four, the latter only three toes. 

 A very striking anatomical difference is the presence in the former of a very powerful 

 cnemial process of the tibia in front of the knee-pan, anotlier being that the former 

 have au ambiens muscle whi;_ the latter lack. 



