MURIDA—SIGMODONTES—HESPEROMYS PALUSTRIS. 113 
are not actually more like Mus than they are like Hesperomys. This 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 obliquely 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 afhinity 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-field Mouse. 
Mus palustris, HARLAN, Am. Journ. Sci. xxxi, 1837, 386 (New Jersey). 
Hesperomys palustris, WAGNER, Suppl. Schreb. iii, 1843, 543.—LECONTE, Proe. Acad. Nat. Sci. Phila. vi, 
1853, 410.— ALLEN, Bull. Mus. Comp. Zool. ii, 1870, 182 (Florida). 
Hesperomys (Oryzomys) palustris, BarrD, M. N. A. 1857, 482 (Georgia and South Carolina).—CougEs, Prow 
Acad. Nat. Sci. Phila. 1874, 184. 
Arvicola oryzivora, AUD. & Bacu., Q. N. A. iii, 1853, 214, pl. 144, fig. 3. 
Hasirat.—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 have already noted how close is the relation between Oryzomys and 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. 
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