iv* 



MONOGHAl'ns OV NOItTU AMERICAN RODBNTIA. 



If! 



II 



entire collections of Rodents contiiined in these Mnseums, nmounting in the 

 aggregate to severiil thousand specimens. No work of the kind hitherto pub- 

 lished rests upon sncli an enormous amount of material, nnd no naturalists arc 

 more competent to elaborate it than the authors of these memoirs have proven 

 tlicmselves to be. Their, work, it is believed, will challenge comparison in 

 points of laborious and conscientious research, of uccnrate and minute detail, 

 and of thorougldy scientific method in study. 



The Rodcntia constitute by far the largest order of Mammals, ond one 

 of the mo.st important from an economic ns well as scientific standpoint. 

 Thougii the species are mostly small and apparently insignificant, their rela- 

 tion? with man arc of much moment. Some of them, like the Beaver, the 

 Muskrut, and others, furnish important articles of commerce ; while a large 

 majority of the species directly aflect the agricultural interests of the nation. 

 Various cpccies occur in countless multitudes, and constitute one of the most 

 serious obstacles with which the agriculturist has to contend in many parts 

 of the country. It is not easy, therefore, to give undue prominence to a 

 group of Mammals, accurate and full information respecting which is essen- 

 tial to the intelligent direction of measures to stay their ravages. In the 

 present work, the technical history of nil the species known to inhabit North 

 America is presented in full, together with their geographical distribution 

 and, in some cases, their habits. The fossil as well as the recent species are 

 considered, and many of the exotic allies, of Mexico and of Central and 

 South America, are also brought under review. 



It is now twenty years sihcc the Rodents of North America were revised 

 by Professor Baird, in his "Mammals of North America". This interval 

 almost exactly coincides with the period of the rise and establishment of the 

 theory of evolution, or latest scientific views of the development of species, 

 and their variability under climatic and other conditions of environment. The 

 Rodents of North America have never before been systematically treated from 

 this standpoint, which necessitates a thorough revision of the whole subject. 

 The authors have thus not only been able to avail themselves of a vastly greater 

 amount of material than that at the command of any other investigators, 

 but they have also studiously applied the sounder principles of modern sci- 

 ence to the elucidation of the subject. They are well known as leaders 

 among American Mammalogists in this line of research, ai.a ■;: eir studk<^8 

 have resulted in placing the subject in an entiiely new light. It is believed 

 that the publication of this volume will murk en era in the history of Ameri- 



