G L I R E S. 



45 



salient and eight re-entering angles, exclusive of the interior emargi- 

 nation of the trefle. In the lower jaw, the first molar commences 

 with a trefle, then follow six triangles, two exterior, three interior, 

 and one posterior ; the second presents five triangles, two exterior, 

 two interior, and one posterior ; the third is narrowed anteriorly, and 

 formed of five triangles, two exterior very small, two interior and one 

 posterior. The line of teeth in the lower jaw presents externally 

 eleven salient angles, including the exterior lobe of the trefle, and nine 

 re-entering angles, including the concavity of the side of the trefle ; 

 internally, eleven salient, the two penultimate very small, and eleven 

 re-entering angles, including the interior lobe and the emargination of 

 the side of the trefle. This dentition is precisely similar to that of 

 Arvicola riparius, Ord. 



Dimensions. — Total length (specimen in spirits), from tip of nose 

 to end of tail, about six inches ; head, one inch and a C;[uarter ; fore 

 leg, three-quarters of an inch ; hind leg, one and a half inches ; tail, 

 two inches. 



Colors. — Entire pilage of the upper parts glossy rufous, darkest on 

 the middle of the head and back ; under parts grayish-white, palest on 

 the abdomen. Fur on all parts dark-lead color at base, and only tipped 

 with the colors just stated. Feet and tail reddish-brown, nearly 

 uniform with the color of the upper parts of the body. Incisors, on 

 their anterior surface, pale orange-yellow. 



Hab. — Puget Sound, Oregon. Specimen in Nat. Mus. Washington. 



This is one of the most handsome little animals of its family, and 

 bears some general resemblance to Arvicola riparias, but is very 

 readily to be distinguished. We find in the notes of the naturalists 

 of the Expedition nothing relating to it, further than that it was 

 obtained at Puget's Sound, Oregon. 



2. Arvicola californicus, Peale. — The California Field Mouse. 



Arvicola californicus, Peale, Zool. Exp. Exp. Mamm. p. 46 (1st ed. 1848). 



Atlas, Mammalogy, Plate VIII, Fig. 1. Adult. 



Subvariegatus rufescenti-fasco et nigra. Corpore hrevi et rohusto, pilis 



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