482 



THE AMERICAN NATURALIST 



[Vol. XLV 



which through the lower and middle Eocene was sepa- 

 rated from Europe. The fact that Tar sins is confined 

 to islands possibly explains why it has remained in so 

 primitive a condition in many ways, though specialized 

 in the limbs which are as yet unknown in any others of 

 this group. 



The general feeders are a larger and more abundantly 

 preserved group. It includes the Notharctidae 4 of North 

 America (to which belong Pelycodus and Notharctus) ; 

 the Adapiidae of Europe 5 (including Adapts and Plesa- 

 dapis) ; the Homunculidae of South American Miocene 

 ( including the genera Homunculus, Pitheculites, Ho- 

 munculites) and lastly the living lemurs of southern 

 Asia, Madagascar and Africa. All have the dentition 

 %, Vi, %, % = 40, and long heads, and apparently ate both 

 vegetable and animal food. The group originated like 

 the foregoing in northern America and migrated south- 

 ward, driven by the change in climate. The earliest 

 known forms are those in the Wasatch of western Amer- 

 ica, and they are likewise the most primitive. Though 

 preserved only in Wyoming and New Mexico, they prob- 

 ably occupied pretty much all of our western plains coun- 

 try, then forested. South America seems to have been 

 isolated from early Eocene times, so that some repre- 

 sentatives of this group probably got into that continent 

 by early Eocene times, i. e., the radiation over North 

 America must have been pretty rapid and general by 

 lower Eocene times. Those in North America after the 

 separation of South America flourished for some time, 

 being especially abundant in the Wind River and Bridger 

 epochs, but with the cold of the Uinta epoch they were 

 crowded south and finally exterminated in North Amer- 

 ica, never more to be widely distributed on that continent. 



285, P 1906! 



•See Schlosser, "Die Affcn, Lemuren, Chiropteren, etc.," des Euro- 

 paischen Tertiars, Theil 1, a. 19-54, 1887. 



•See Ameghino, Anal. d. Museo Nac. d. Buenos Aires, Vol. 15, PP- 

 424-429, 1906. 



