388 GEOGRAPHICAL AND GEOLOGICAL DISTEIBUTION". 



and Central Asia, and practically the whole of the North American 

 continent, although it appears to be absent from the immediate 

 Pacific coast. A well-marked variety of this form, by many natu- 

 ralists considered to be a distinct species, is the broadly distributed 

 silver- fox (C. Virginianus), which alone of the different varieties 

 is represented in Central America. The burrowing-fox (C. velox) 

 is an inliabitant of the interior region included between the (low- 

 er) Missouri and Saskatchewan rivers and the Cascade Mountains. 

 Over a considerable part of North-Central Asia — Tartary, Mon- 

 golia, Siberia — the common fox is replaced by the corsac or steppe- 

 fox (C. corsac), a closely related species. The most northerly species 

 of fox is the Arctic fox (C. lagopus), a circumpolar mainland form, 

 occurring also in Iceland and Spitzbergen. 



The Canidao appear to date from the (Upper) Eocene period, 

 and not impossibly the genus Canis is itself represented in the form 

 that has been described by Cuvier as Canis Parisiensis. Less doubt 

 attaches to the C. Filholi, from the phosphorites of Central France, 

 whose position, however, still remains somewhat uncertain. Barring 

 these two forms, the oldest representatives of the family are seen in 

 the genera Galecynus and Amj^hicyon, which apjiear in Europe in 

 the Upper Eocene and Lower Miocene respectively. In America 

 Galecynus is unknown prior to the Oligocene (or Lower Miocene — 

 White River formation), to which period must be referred the most 

 ancient undoubted remains of the family in the New World. To this 

 genus, whose representatives appear to have been very abundant 

 during the Miocene epoch, the existing species of dog are referred 

 in their line of descent by Filhol and Cope. Canis, which in the 

 Miocene is associated with a number of allied generic forms — Tem- 

 nocyon, Oligobunis, ^lurodon (with feline and hyasnoid relation- 

 ships), in addition to those above named — becomes the dominating, 

 if not the only, type in the Pliocene, where also we meet with the 

 earliest existing species, the wolf and coyote (Western Territories 

 of the United States). The Post-Pliocene dejiosits contain the re- 

 mains of the wolf, fox, and dog.* 



* Mr. J. A. Allen has recently described a species of extinct do(j (Pachy- 

 cyon robustus) from Ely Cave, Lee County, Viririnia, wliicli in many respects 

 departs widely from tiie type of any of tlie ordinary wild or domesticated 

 races. In its freneral proportions, the shortness of the leers, &c., it more 

 nearly approaches the badgers. Its geological horizon has not been absolutely 

 deterniined. 



