144 FAUNA AMERICANA. 



Species. 

 6. Arvicola Petinsylvcmica* 



ists.) A more complete description occurs in Maj. Long's ex- 

 ped. to the Rocky Mountains, vol. 1, p. 54. 1819 — 20, where 

 Mr. Say has adopted in an unqualified manner the name given 

 by Mr. Ord. Thus it remained until the attention of these gen- 

 tlemen was particularly directed to the dentition of this animal- 

 by the observations of M. Desmarest, in his '■'' Maimnalogie.''' 

 They now described the animal as an Arvicola, (to which, in 

 reality, it belongs.) Finally, observing that the molar teeth of 

 the animal were furnished with " roots^'''' they have constructed 

 the new genus " JVeotoma.'''' (The division is sufficiently novel, 

 it must be confessed, and if adopted, would destroy the whole 

 fabric of classification.) 



F. Cuvier has not mentioned the roots of the molar teeth of 

 those species from which he has drawn the characters of the 

 genus Arvicola ; a circumstance so apt to vary even in the teeth 

 of the same animal, this able naturaUst considered as beneath 

 his notice in a work which has for its object a description of 

 the teeth considered as zoological characters. (" Dents des raam- 

 miferes considerees comme characteres zoologiques.") Not- 

 withstanding this, Messrs. Say and Ord, consider the " roots" of 

 the teeth as of sufficient importance to establish generic distinc- 

 tions. In the present instance, at least, they admit, that in the 

 softness of the fur, and in the tail being clothed with hair, the 

 ''^ jYeotoma''' resembles the Arvicola; to which! would add, that 

 in all other external characters, this species resembles the Ar- 

 vicola, as closely as the different species of that genus resemble 

 each other. 



Tije description which Messrs. Say and Ord have given of 

 the iceth of the " Neoloma,''^ (always excepting the roots.) so 

 exactly corresponds with M. Cuvier's description of the teeth 

 of the genus Arvicola, that we are tempted to believe the for- 

 mer to be a literal translation. (Vid. Dents des mammifcres, 

 &.C. F. Cuvier: first division, page 155.) 



