884 



MONOGRAPnS OP NORTH AMERICAN RODENTIA. 



m 



'U 



introduction and increase in New Jersey are given mainly on the authority 

 of Mr. Jillson, and are fully covered by Mr. Jillson's later and more detailed 

 account already quoted. 



From the foregoing, it will be seen that from the single pair introduced 

 accidentally to the fields about Tuckerton in 1867 — only ten years ago — the 

 species has spread over a belt of country some thirteen miles in length and 

 probably several miles in breadth, and that its numbers already render it a 

 farm pest, which evidently cannot be soon, if ever, wholly eradicated. It 

 shows, furtliermore, that the species is capable of multiplying in. a region 

 quite different from its original habitat Whether the changed conditions 

 will ultimately modify materially its habits and structure remains an inter- 

 esting question for later investigators. 



Tadle CXXIV.— Measurements of seven skulls 0/ SPEHMOPUlLUa franklini. 



* In Maaeum of Comparative ZuJilogy, Cambridgo, Man*. 



