MATTHEW, CLIMATE AND EVOLUTION 233 



The primitive character of the viverriiies is especially seen in their 

 imperfect differentiation of shearing and crashing back teeth, their 

 rather short limbs, long bodies, long tails and relatively small brain 

 capacity. 



Hycenida'. — The family Hya-nidro is generally regarded as a specialized 

 offshoot from the Viverrids and is apparently connected with the Euro- 

 pean Miocene viverrids by a series of intermediate forms. The latest 

 development of the race, the genns Hycena, inhabited Enrope and Cen- 

 tral Asia and China in the Pliocene and Pleistocene bnt is now found 

 only in India, Africa and southwestern Asia. 



Felida. — The Felidte are almost as cosmopolitan as the clogs and are 

 even more uniform in type, the cheetah being the only marked living 

 variant. A notably different specialization is shown in the extinct 

 machferodonts or sabre-tooth tigers, and in the Tertiary sequence in 

 Europe and America we find approximate genetic series, parallel in the 

 two countries, by which the true cats and machrerodonts converge towards 

 a common primitive type, in which the upper canines are moderately 

 elongated. According to this phylogeny, the clouded tiger of Sumatra 

 and Java is the most primitive living felid, while the double series in 

 Europe on one hand and North America on the other, would indicate 

 northern Asia as the center of dispersal of the race. The range of some 

 of the modern species is very great. The puma extends in the New 

 World from Alaska to Patagonia, the tiger in the Old World from Man- 

 churia to Java. We may note, however, that the tiger is regarded by 

 Blanford as a recent immigrant into southern India; while, on the other 

 hand, it is known that the northern range of the lion has been pro- 

 gressively restricted during prehistoric and historic times from northern 

 Europe to its present limits of southwestern Asia and Africa. 



PINNIPEDIA 



When dealing with littoral and marine mammals we must expect to 

 find the conditions of their evolution somewhat different. If the hypoth- 

 esis be valid that the progressive refrigeration of the polar regions was 

 the dominant cause of evolutionary progress and geographic dispersal, 

 an examination of the map will show that the xirctic-North Atlantic basin 

 affords the most favorable region. The Arctic basin centers around the 

 pole, and a broad shelf of shallow water encircles it, extending as far 

 south as latitude 45°. The North Pacific basin was closed to the north- 

 ward by the Alaskan land-bridge during a large part if not all of the 

 Tertiary, and its shores plunge suddenly to great depths, margined by 



