1852.] 161 
B. Dentes primores sulco medio nullo. 
6. G.rufescens, mollipilosus, saturate cinereus, supra rufo-tinctus, lateribus 
et infra albo-tinctus, auribus brevibus, cauda mediocri albo-pilosa, primoribus su- 
perioribus intus marginatis. 
Large. Small. 
Length from nose to root of tail, 3 : : 8 5:4 
6“ failure te ‘ A ‘ x i M 1:9 Q. 
Fore foot to end of third claw, - j Je °8 
Hind foot to end of third claw, i 6 4 1°15 °9 
Thomomys rufescens Wied, Nov. Act. Leop. Car. Akad. (1839) 19, 377; 
Schinz, Syn. Mam. 2, 134. | 
Geomys borealis Bachman, Jourr. Ac. Nat. Sc. (1839) 8, 103; Richardson, 
Report British Ass. 2, 150; Schinz, Syn. Mam. 2, 136. . 
Geomys Townsendt Bachman, Journ. Ac. Nat. Sc. 8, 105; Richardson, Zool. 
of Beechey’s Voy. 12; Schinz, Syn. Mam. 2, 137. : 
?Oryctomys (Saccophorus) Botte Eydoux, Voy. Favorite, (1837) 1, 2, 23. 
Ascomys rufeseens Wagner, Schreber Saugeth. Suppl. 3, 387. 
Ascomys borealis Wagner, ibid. 391, 
Ascomys Townsendt Wagner, ibid. 391. 
Pseudostoma borealis, Aud. & Bachm. Quadr. Am. 3, pl. 142. 
Saccophorus borealis Gray, Cat. Brit. Museum, 149. 
“° Geomys bursartus Richardson.” Gray, ibid. 
Two specimens from Columbia river, J. K. Townsend; the larger one labelled 
<¢ Pseudostoma Townsendi (Rich.),”’? the smaller one “‘ Pseudostoma borealis.”? 
The fur is very fine and shining, dark cinereous, tipped on the back with ru- 
fous, on the sides and beneath with white; on the chin and feet the hair is almost 
entirely white. The whiskers are gray, and nearly as long asthe head. The 
ears are short but distinct. The tail is covered with whitish hair; the upper in- 
cisors are slender, and marked with a very fine line at the inner margin of the 
anterior face. 
This species (and probably all the others of this division,) has the inferior 
incisors much more slender than those above described; the fossorial claws of the 
anterior feet are also much smaller, so that even if the teeth were wanting no 
difficulty would ensue in the determination of the species. 
The specimen of the Prince de. Wied was found on the plains of the Missouri 
but his description agrees so acctfrately with our specimens, that there can be no 
doubt of their identity. Dr. Bachman mentions his want of faith in the specific 
difference of the two specimens described by him, and gives them as distinct on 
the authority of Richardson. The latter remarks in Beechey’s Voyage, that “G. 
Townsendi is distinguished from G. borealis by its longer tail.” It must be ob- 
served, however, that in Dr. Bachman’s measurements, the small specimen of G. 
borealis, five inches and a half in length, has the same length of tail as the large 
one, which is two inches longer. The specimen of G. Townsendi of the same 
size as the large G. borealis, hada tail nine lines longer, which is in exact pro- 
portion to the small specimen of G. borealis. The large specimen now before 
me, (which is labelled G. Townsendi,) has the precise proportions of the G. 
borealis described by Bachman, and is probably the identical one examined by 
him. On careful examination, I find that the tail does not taper regularly as in 
the other specimen, and, moreover, at its apex a distinct cicatrix is visible. I 
think we are therefore warranted in concluding that Geomys borealis is founded 
in a mistake. 
I do not know what Mr. J. E. Gray means by quoting “ Geomys bursarius 
Richardson, Report of British Association, 1836, 156,’? as a synonym of this 
species. Sir John Richardson, on page 9 of the Zoology of Beechey’s Voyage 
mentions that Mus bursarius of Shaw is a Geomys, and on page 12 describes C. 
borealis, thereby implying that he considered them as distinct species. 
There is a third specimen in the museum of the Academy labelled ‘ Pseudos- 
toma Richardsonii, Columbia river, J. K. Townsend,” which only differs from 
