408 [ OcTroBER, 
Pennant with the Arv. agrestis of Europe. It is very easily distinguished from 
any other of the genus that I have seen in America, by the furrow on the inner 
margin of the superior incisors, and by the large antitragus of the ear, which 
completely closes up the auditory passage as witha valve, the last character - 
showing that it is peculiarly fitted for an aquatic life. It is generally pointed 
out by American naturalists as the A. xanthognathus of Leach, a species which 
I have never had the good fortune to see, and which I scarcely believe has ever 
been found far from the Arctic regions. As for its habits, it delights in marshy 
places, and swims and dives with much dexterity. It leaves the lower grounds, 
however, and is often found in upland meadows. Formerly it was very common 
in the vicinity of New York. ‘This was before the advance of population on that 
favored spot had destroyed everything connected with nature, except the vices 
of man. 
There is generally quoted in connection with this species of Arvicola, a figure 
in Wilson’s Ornithology, vol. vi., pl. 50, which has nothing characteristic about 
it, and may as well be said to represent anything else. 
8. ARVICOLA BOREALIS. Capite magno et obtuso, auribus brevibus, sub pilis 
occultis. Tarso subtus dense piloso. Cauda sparse pilosa, supra nigrante, sub- 
tus fusco cinerea. é 
Hab. In provinciis borealibus. (R. Island, Mr. Powel.) <A. borealis Rich., 
loc. p. 1273 Wiegman?s Anchiv., 18435 part)\2.)p..63.) (Schinzesle-s. pecoul. 
Wagener, l. c. 593. 
Hair very shining, dark plumbeous, above and on the sides tipt with bright 
brown and black, so as to have a somewhat variegated appearance, beneath with 
gray very slightly tinged with brown. Head large,short and blunt; ears round, 
entirely concealed under the fur, hairy both within and without; antitragus large, 
semicircular. Feet light cinereous brown, covered with short shining hair, the 
tarsi beneath densely hairy; thumb tubercle, with a short, straight blunt nail. 
Tail thinly covered with hair, above dusky, beneath brownish grey. 
Length in. 6:2; head 1:3; ears -25; foreleg -9 ; hind leg 1-7; tail 2. 
9, ARVICOLA CALIFoRNICUS. Subvariegatus rufescenti-fusco et nigro. Corpore 
brevi et robusto, pilis speciem hirsutiei habentibus, revera tamen mollibus et 
levibus. Auribus submagnis, pene sub pilis occultis. Cauda supra fusca, sub- 
tus fusco-cinerea. 
Hab. In California. A. Californica Peale, Zool. Expl. Ex. Quadrupeds, 46. 
Body short and thick. Hair rather long, very shining, at the roots plumbeous 
black, above and on the sides tipt with reddish brown and black in such a man- 
ner as to give it a hirsute appearance, which in reality it does not possess, be- 
neath with grey. Head blunt; ears rather large, almost concealed under the fur, 
hairy both within and without. Feet covered with short shining, greyish brown 
hair; thumb tubercle, with a compressed blunt nail. Tail above brown, beneath 
cinereous brown. 
Length 5-7; head 1-3; ears -46; fore leg 1; hind leg 1-5; tail 1-5; fur -45. 
The dentition differs from that of A. riparius as follows: In the upper jaw the 
second interior triangle of the first tooth is furnished with a small, sharp poste- 
rior lobe, and the interior triangle of the second has likewise a sharp posterior 
lobe. In the lower jaw the first tooth is formed of 8 triangles, 1 anterior, which 
may rather be called an oval, 1 posterior, 3 exterior and 3 interior. ‘The line of 
teeth in the upper jaw differs in having internally 9 salient and 9 re-entering 
angles, and in the lower jaw in having externally 10 salient and 9 re-entering 
angles, and internally 12 salient and 11 re-entering angles. 
10. Arvicoua occipenTALIs. Pilis mollissimis et tenuissimis, extremitatibus 
superioribus rufis sine ulla nigri adrnistione. Auribus sub pilis oceultis. Cauda 
sub compressa, supra et subtus concolore rufa. 
Hab. In tervitorio Oregonensi. A. occidentalis Peale, 1. c., 45. 
Hair dark plumbeous, very soft and fine, above tipt with bright rufous without 
any admixture of black, beneath with grey. Head blunt; ears round, entirely 
concealed under the fur, hairy only on the outside; antitragus rather shorter than 
usual. Feet covered with short shining, ru'ous hair; thumb tubercle, with a 
