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PROCEEDINGS OF THE ACADEMY OF 



without seminal agency, and that the same variety in this way has appeared 

 in widely-separated districts. 



4th. As the discoveries of Darwin have shown in many cases, varieties to be 

 the parents of species, species may originate in widely-separated localities 

 by bud variation. 



A Sketch of the Classification of the American ANSERINiE. 

 BY B. H. BANNISTER. 



The following remarks are based upon an examination of the specimens of 

 American geese in the collection of the Smithsonian Institution. 



The subfamily Anserina? by many recent authors is made to include the 

 genera Dendrocygna and Chenalopex, and doubtless correctly. In the present 

 paper, however, we shall not consider these genera, leaving them provision- 

 ally out of the subfamily; if included, they would form at least one well 

 marked section, following those we are about to describe. 



The distinguishing characters of the Anserime, as thus limited to the true 

 geese, are, the lengthened tarsus, covered with hexagonal or subquadrate 

 scales; the neck more elongated than in the ducks and less so than in the 

 swans ; the short, high bill gradually narrowing toward the tip, which is 

 altogether composed of the large recurved nail ; together with the more or 

 less terrestrial habit of life, and the usually similar plumage of the two 

 sexes. 



The geese of the North American continent have been long known, and 

 being for the most part closely allied to, and in many cases identical with, 

 well known European forms, they fall readily into the systematic subdivisions 

 based upon the latter. In the temperate regions of South America, however, 

 the Anserinae are of a rather aberrant type, and have been less completely 

 studied. They differ chiefly from the North American and European species 

 in possessing metallic tints on the plumage, and in having in two of the 

 genera the coloration of the two sexes Widely different. These differences 

 appear to be exclusively regional, none of the aberrant forms being found in 

 North America, and vice ver.su. 



Another basis of division of the American Anserinre is found in the 

 presence, in two species one North American aud the other a Southern form 

 of deep rough superorbital depressions and reversed relative proportions of 

 the tarsus and middle toe, together with an exclusively sea- coast habitat, aud 

 a carnivorous diet, corresponding iu some of these respects to the Oidemise 

 and Somaterise amongst the ducks. 



These latter characters we have taken as the basis of the two sections into 

 which we divide the subfamily, as at present considered, since they correspond 

 with equivalent characters in one of the subdivisions of the Fuligulinse. The 

 presence of the deep superorbital depressions is a very general character 

 amongst the carnivorous natatores, though not universal. 



The following is offered as an outline of the divisions and genera of the 

 subfamily, noting briefly the principal generic characters, the American spe- 

 cies and their geographical distribution. The principal characters of the 

 subfamily have been already given at sufficient length. 



Subfamily ANSERINE. 



Section A. Anserese. Habits terrestrial ; tarsi longer than middle toe with 

 claw, skull without superorbital depressions. 



a. Typical. Plumage without metallic reflections, color of sexes invariably 

 similar. 



1. ANSER, Vieill. 



Gm. Char. Bill as short as head or shorter, gaping at the sides, the lamel- 



[Nov. 



