482 



was said 

 Union. 



U. S. P. R. R. EXP. AND SURVEYS ZOOLOGY GENERAL REPORT. 



to be abundant in the prairie. That of Audubon and Bachman was found near Fort 



List of specimens. 



HESPEROMYS (OEYZOMYS) PALUSTRIS. 



Rice-field Mouse. 



Mus palustris, HARLAN, Sill. Am. Jour. Sc. XXXI, Jan. 1837, 386, (Fast Land, near Salem, N. J.) 



Isis, 1840, 178. 

 Ilesperamys palustris, WAGNER, Suppl. Schreb. Ill, 1843, 543. 



LECONTK, Pr. A. N. Sc. Phila. VI, 1853, 410. 

 Arvicola omjziwra, AUD. & BACH. N. Am. Quad. Ill, 1853, 214 ; plate cxliv, fig. 3. 



SP. Cu. Color above mixed black and pale brownish ash, sometimes with a tinge of yellowish brown on the sides 

 beneath ashy white without any distinct separating line. Tail dusky, scarcely lighter beneath. Feet whitish. For generic 

 characters see page 458. 



This species is quite different in appearance from the ordinary species of Hesperomys, as found 

 in the United States, and indeed would be taken rather for an Arvicola or Sigmodon than anything 

 else. In size it exceeds any North American species, unless that from Santa Clara, California, 

 be an exception. The ears are unusually short for the genus, in the dried skin, scarcely projecting 

 beyond the skin, although distinctly visible from the side; they are rather higher than broad 

 in life, but nearly orbicular in the skin, the edge completely rounded without any angle. 

 The antitragus is rather lower and less distinct than in H. leucopus. The ear has much th ) 

 appearance of Arvicola in respect to its hairs, which are long and coarse instead of being short 

 and velvet-like, as in H. leucopus. A peculiarity of this group is seen in the existence of i 

 patch on the concavity of the ear of longer hairs than elsewhere, a short distance from th ; 

 naked area around the meatus. 



The eyes in this species are small, appreciably less than in H. leucopus. There is a peculiar 

 appendage to the lower internal corner of the nostril, in the shape of a cartilaginous pad, 

 indented by two furrows which meet below, enclosing an elongated depressed eminence. The 

 axes of these eminences of opposite sides would, if produced, meet on the lower border of the 

 nose ; in fact, the pads themselves are very nearly in contact. Something similar is seen in If. ; 

 leucopus, but it is much less conspicuous. The upper lip is cleft or acutely emarginate to the 

 base of the incisor ; the furrow, continued thence to the nose, is shallower than in H. leucopin, 

 and does not permit as great a separation of the parts, causing the lip to appear less deeply 

 cleft. 



The feet present many striking peculiarities, among which is the complete nakedness of the 

 sole from the extremity of the heel. There are six tubercles, the posterior one very long aid . 

 narrow, as in Mus, measuring 0.15 of an inch in one specimen, or more than one-sevenih 



