■2m GEOGRAPHICAL ZOOLOGY. [i'Aiit iv. 



Extinct Sciurida'. — These are tolerably aLundant. The genus 

 Sciurus appears to be a remarkalily ancient form, extinct species 

 being found in the JNIiocene, and even in the Upper Eocene 

 formations of Europe. Spermophilus goes back to the Upper 

 ^Miocene; Ardomys to the Newer Pliocene. Extinct genera are, 

 Bracliymys, Lithomys and Phsiardomys, from the European 

 Miocene, the latter said to be intermediate between marmots 

 and squirrels. 



In North iVmerica, Sciurus, Tamias, nnd Ardomys occur in the 

 Post-pliocene deposits only. The extinct genera are Isdiyroinys, 

 from the Upper Miocene of Nebraska ; Paramys, allied to the 

 marmots, and Sciuravus, near the squirrels, from the Eocene of 

 Wyoming. 



Here w^e have unmistakable evidence that the true squirrels 

 {Sciurus) are an Old World type, which has only recently entered 

 North America ; and this is in accordance with the comparative 

 scarcity of this group in 8outh America, a country so well 

 adapted to them, and their great abundance in the Oriental 

 region, which, with the Palaearctic, was probably the coun- 

 try of their origin and early development. The family, how- 

 ever, has been traced equally far back in Europe and North 

 America, so that we have as yet no means of determining where 

 it originated. 



Family 62.— HAPLOODONTID.E.— (1 Genus, 2 Species.) 



General Distribution. 



The genus Haplooclon or Aphduntia, consists of two curious 

 rat-like animals, inhabiting the west coast of America, from the 

 southern part of British Columbia to the mountains of Califor- 

 nia. They seem to have affinities both with the beavers and 

 marmots, and Professor Lilljeborg constitutes a scpaiatc family 

 to receive them. 



