Fauna Boreali- Americana, 357 



philus, which has been separated from that of Marmo tta in consequence 

 of the animals composing it possessing cheek-pouches, and Diplostoma, 

 or Camas Rat, both established by Dr. Richardson, are the most interesting. 

 From the combined characters of the former, it appears to unite the mar- 

 mots with the hamsters, and in it are contained eight American species, 

 seven of which are severally named after the adventurous explorers of these 

 inhospitable regions, Parry, Richardson, Franklin, Beechey, Douglas, Say, 

 and Hood. Whilst we utterly disclaim the slightest wish of detaching a 

 single laurel from such brows, we cannot forbear taking this opportunity of 

 entering our protest against this wholesale complimentary nomenclature, 

 which, in these instances, appears peculiarly inappropriate, since the reput- 

 ation of our gallant discoverers, indelibly engraven on every chart in the 

 world, can scarcely be supposed to derive any material addition from hav- 

 ing their names bestowed upon rats and mice ; the compliment, if any, 

 seems here in fact to be reversed, infinitely greater honour being thus con- 

 ferred upon the Spermophili. The other new genus Diplostoma is extremely 

 peculiar, inasmuch as the cheek-pouches, which are lined with hair, do not 

 communicate with the mouth, which is a mere perpendicular slit behind the 

 exserted incisors, but open in front of it. 



Other genera of recent foundation, as Neotoma (divided from the Lem- 

 mings), Meriones (formerly a Jerboa), Tamias (the Ground Squirrels), 

 Geomys (Sand Rats), Aplodontia (nearly allied to the last, and scarcely 

 established from living specimens), Lagomys, and Lipiira (both separated 

 from the hares) differ, more or less, in their teeth, from genera formerly 

 acknowledged. Were it possible for man, with his imperfect faculties, to 

 fabricate a perfect system, these minute subdivisions might materially expe- 

 dite so desirable a consummation ; but as that is confessedly beyond the 

 reach of human power, it becomes a question worthy of serious consider- 

 ation, whether they do not rather impede than hasten the progress of science 

 by overburthening the memory. It is by no means established what pre- 

 cise characters of an animal ought to be considered as sufficiently influen- 

 tial to warrant its generic separation from others nearly allied to it. The 

 shape and arrangement of the teeth have been usually selected as forming 

 the most important ; but the order Rodentia appears to us an exception to 

 the rule. Of large groups of these animals the mode of life is precisely 

 similar, and the presence or absence of two or three bands of enamel on the 

 crowns of the grinders, or a different direction of their waving lines, which 

 do not seem to aifect their manner of using them, appear to be characters 

 of scarcely sufficient consequence to divide them into separate types. In 

 the more general divisions, such as squirrels, mice, hares, porcupines, &c., 

 so much difference is at once observable in the aggregate of their charac- 

 ters, which positively and materially influence their modes of subsistence, 

 that the correctness" of their separation from each other admits of no dis- 

 pute ; but if the form of the teeth alone be considered as generic distinc- 

 tions, each individual species throughout this extensive order might become 

 a new type, as no two are precisely similar in their dentition. 



The Canada Porcupine (^ystrix pilosus Cateshy\ which lives on the bark 

 of the larch and spruce fir, willow, &c., is described as a sluggish and un- 

 sightly animal, seldom moving far from one spot, provided its food be abun- 

 dant. The following account of the use of its spines is an important fact : 

 — " It is readily attacked by the Indian dogs, and soon killed, but not 

 without injury to its assailants ; for its quills, which it erects when attacked, 

 are rough with minute teeth, directed backwards, that have the effect of 

 rendering this seemingly weak and flexible weapon a very dangerous one. 

 Their points, which are pretty sharp, have no sooner insinuated themselves 

 into the skin of an assailant, than they gradually bury themselves, and travel 

 onwards, until they cause death, by wounding some vital organ. These 

 spines, which are detached from the porcupine by the slightest touch, and 



