156 THE ARCTOG^IC REALM. [CHAP. 



to those of modern lemurs. These early forms differ however from 

 the latter in that the first of the three lower premolar teeth does 

 not assume the form and functions of a canine. Another well- 



FlG. 32. RIGHT UPPER CHEEK-TEETH OF TWO SPECIES OF THE] LEMUROID 



GENUS Microchtxrus. Nat. size and enlarged. 



known European lemuroid is Adapts, of the European Oligocene, 

 differing from all living forms in having four pairs of premolar 

 teeth. 



With the Oligocene, lemuroids seem to have disappeared from 

 western Europe, and they apparently ceased to exist about the 

 same date in North America, after which the entire order of the 

 Primates is unrepresented in the latter country. At the present 

 day, as we shall see, lemuroids are confined to the Malagasy, 

 Ethiopian, and Oriental regions ; but at what epoch the southern 

 migration took place cannot yet be determined. 



Omitting mention of the bats, we pass on to the Insectivora, 

 among which we have the mole family (Talpidce) 

 distributed over the whole of the Holarctic as well as 

 the Sonoran region, although all the genera but one are distinct 

 on the two sides of the Atlantic ; the single common type being 

 the shrew-moles (Urotrichus\ which have one species in Japan 

 and another in the United States, thus affording an instance of the 

 near affinity of the fauna of eastern Asia to that of North America. 

 The earliest known fossil forms which have been assigned to the 

 typical genus Talpa occur in the upper Oligocene strata of Europe, 

 while in the middle Oligocene the family is represented by the 

 allied Amphidozotherium (Protalpa). The shrews (Soriddce)^ 

 which likewise date from the Oligocene of the Continent, range 

 over the whole realm, and also enter the Austro-Malayan region 



