MURIDiE— SIGMODONTES-DESPEROMYS PALUSTErS. 113 



are not actually more like Mas than they are like Hesperomys. Tliis cranial 

 resemblance to Old World Murines is strikingly borne out by the external 

 characters of the animal, which, in general appearance, looks really more like 

 a small house-rat than like one of our New World Hesperomys. The resem- 

 blance is at a climax in the very long, scant-haired tail, on which not only are 

 the annuli distinct, but the granular plates perfectly evident, at least along the 

 upper side of the tail. The aquatic nature of the animal is indicated by the 

 feet and ears. The former are much like those of Fiber in being naked and 

 granular beneath, velvety-pilous above, and especially in having such long toes, 

 slightly webbed at base and set oblicpiely on the metatarsus, to facilitate their 

 "feathering" during their forward motion in swimming. The low, orbicular, 

 thickly hirsute ears are specially provided with a fluffy tuft inside to guard 

 against entrance of water, and the antitragus is well developed for the same 

 purpose. While the general construction of the feet is much as in Fiber, the 

 tuberculation of the soles is like that of Mus. 



On the whole, we may consider this animal as (next after Onychomys 

 leucogaster, which leans so strongly toward Arvicola through Evotomys) the 

 most aberrant of the North American group of small Hesperomys, sharing 

 many features of the larger Sigmodon, showing a slight approach, by analogy 

 at least, to Fiber, and having much real affinity with the Old World Mus 

 proper. It is certainly the nearest to typical Mus of anything we have in 

 North America ; it inclines toward Mus proper, and especially to Sigmodon* 

 much as Onychomys, our only other subtypical section of Hesperomys, does 

 toward Arvicola. 



HESPEROMYS (ORYZOMYS) PALUSTRIS, (Harl.) Wagner. 



Rice-fleld Mouse. 



Mus palustris, Harlan, Am. Journ. Sci. xxxi, 1837, 386 (New Jersey). 



Hesperomys palustris, Wagner, Suppl. Scbrob. iii, 1843, 543. — LeConte, Proc. Acad. Nat. Sci. Phila. vi, 



1853, 410.— Allen, Bull. Mus. Cotup. Zool. ii, 1870, 182 (Florida). 

 Hesperomys {Oryzomys) palustris, Baird, M. N. A. 1857, 482 (Georgia aud South Carolina). — Coues, Proc. 



Acad. Nat. Sci. Pbila. 1874, 184. 

 Arvicola oryzivora, Aud. & Bach., Q. N. A. iii, 1853, 214, pi. 144, fig. 3. 



Habitat. — South Atlantic and Gulf States, especially in maritime por- 

 tions and in rice-fields. Kansas ! (Goss). Mexico (Sumichrast). Jamaica?? 

 The specific characters of this animal are necessarily involved with 



* We Lave already noted how close is the relation between Oryzomys aud Sigmodon, showing that 

 the former is as much to be considered a section of Sigmodon as of Hesperomys, and that Sigmodon itself 

 is hardly or not more different from ordinary Hesperomys than Oryzomys is. 



8 M 



