1883.] NATURAL SCIENCES OF PHILADELPHIA. 275 



Here ngain, therefore, the variation is reduced to an insignifi- 

 cant amount — to 4 and 2 per cent. 



It has been further objected, that " a more logical classification 

 of mammals " than that which has been followed in my paper, 

 would reveal facts materially contravening my tabular statements, 

 but Prof. Gill fails to inform us what this " more logical classi- 

 fication " may be, and it therefore becomes impossible to theorize 

 on his premises.^ The distinguished naturalist of Washington is, 

 however, certainly in error when he maintains that the Arctamer- 

 ican fauna has 4 (instead of 2 — Haploodontidae and Zapodidae — 

 or at the utmost, including the not generally recognized Antilo- 

 capridse, 3) peculiar families ; nor can we understand from his 

 data how, if 29 Eurasiatic genera are represented in Arctainerica, 

 only 23 Arctamerican genera are developed in Eurasia. 



From what has alread}^ been said it will be seen that there is 

 nothing in either Mr. Wallace's or Prof. GilPs arguments which 

 might tend towards altering my views on the question at issue ; 

 and I must therefore still maintain, in the face of the evidence 

 before us, that, in m}' judgment, there is not even the shadow of 

 a peg upon which to hang the Nearctic (as distinct from the 

 Palamrctic) region of zoogeographers. 



' There can be no doubt that certain emendations to the classification 

 followed might have been advantageously made ; as, for example, by the 

 introduction of the genus Cariacits; but the very few alterations that 

 could have been suggested through the works of the most recent, and, as 

 usually recognized, most competent authorities on the subject of the 

 mammalia, would pioduce no really appreciable difference in the result. 



