1853.] 409 



compressed sharp nail. Tail slightly compressefl, rufous, of the same color 

 both above and below. 



The dentition is the same in every respect as in Arv. riparius. 



We are indebted for this pretty animal, as vi'ell as for the precedino; species, 

 to the researches of Mr. Titian Peale, who vv'as one of the Naturalists of the 

 United States Exploring Expedition, under the command of Capt. Wilkes. 



11. Arvicola pinetortjivi. Pilis plumbeo-nigris, supra extremitatibus fuscis, 

 subtus argenteo-cinereis. Oculis minimis, vix evidentibus. Auribus sub pilis 

 occultis. Pedibus brevibus. Cauda brevi, obtusa, pilosa. 



Hab. In Carolina et Georgia in cultis. Vulg. Mole Rat or Ground Mouse. 

 Psammomys pinetorum Leconte, Ann. Lye. 2, 133, tab. 2. Arv.pinetorum Aud. 

 and Bach. Quadr. N. A., Vol. ii. p. ,216. Wagner, 1. c. p. 591. Schinz., 1. c. p. 

 249. 



Body cylindrical. Hair short, shining, plumbeous black, above tipt with brown, 

 beneath with silvery grey. Head large, short and blunt ; eyes very small, scarcely 

 visible ; ears small, roundish, hairy within and without, entirely concealed under 

 the fur; antitragus short, flat, semicircular. Legs short, brown, covered with 

 short shining hair; thumb tubercle, with a compressed, curved nail ; nails of the 

 toes long and slender, naked (no hairs projecting over them as in every other 

 species.) Tail very short, blunt and hairy. 



Length 3-8 ; head 1-1 ; ears -15; fore leg ? ; hind leg -8; tail '7. 



The dentition of this species, and of the following, differs very much from that 

 of any others which I have examined. The molars in the upper jaw are precisely 

 like those of the conamon European species ; while in the lower jnw they are 

 widely different. Upper jaw: the first molar is composed of 5 triangles, 1 an- 

 terior, 2 exterior and 2 interior ; the second of 4 triangles, 1 anterior, 2 exterior 

 and 1 interior: the impressed spaces on the crowns of the teeth, in the posterior 

 interior trian^ile of the first and second teeth, are rectangularly oblong ; the third 

 molar is formed of three triangles, 1 anterior, 1 exterior and 1 interior, and ends 

 in a three-sided piece, which is rounded at its apex, and deeply cut into on the 

 interior side by the last re-entering angle. The upper line of dentition consists 

 externally, of 9 salient and 8 re-entering angles, and internally, of 8 salient and 

 7 re-entering angles. In the lovA^er jaw^ the first tooth begins with a trefiie, then 

 follow 6 triangles, 2 exterior, 3 interior and 1 posterior ; the secondof 5 triangles, 

 2 exterior, 2 interior and ] posterior ; the third is narrowed anteriorly, and formed 

 of 3 triangles, 1 anterior, 1 intermediate and 1 posterior. 



The lower line of teeth consists, externally, of 7 salient and 6 re-entering 

 angles, with two emarginations on the external face of the last tooth, internally, 

 of 11 salient and 10 re-entering angles. 



Previous to the year 1810, this little animal, although well known in the pine 

 region of lower Georgia for its depredations in the cultivated fields of the inhabit- 

 ants, had not made its appearance in the oak lands. The first one that I ever saw 

 was at that time brought to me as a great curiosity ; since then they have become 

 extremely common, and very destructive to sweet potatoes and ground nuts. 

 How long they have been known in South Carolina I have no means of ascer- 

 taining. 



Its life is wholly subterranean ; it is therefore never seen except when acci- 

 dentally or designedly turned up from beneath the surface. 



12. Arvicola scalopsoides. Capite magno et obtuso ,* auribus parvis margins 

 solo exteriore piloso, sub pilis occultis, tarso subpiloso. Supra castaneus subtus 

 cinereus. 



Hab, In Pennsylvania. A. scalopsoides Bachm. Journ. Acad. Sci., Phil., vol 

 viii. p. 299. 



Hair shining, plumbeous, above tipt with chesnut slightly mixed with blackish, 

 beneath cinereous tipt with gi;ey, the latter color tolerably distinctly separated 

 on the sides from the former. Head large and blunt ; ears rounded, hairy in- 

 wardly on the upper edge only, concealed under the fur ; antitragus small, semi- 

 siicular; whiskers grey, longer than the head ; feet covered with short shining, 



