116 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
This remarkable rat has hitherto only been reported from the Southern 
Atlantic seaboard, where it is said to be abundant, particularly in the rice dis- 
tricts. It is eminently aquatic; in this respect equaling the Arvicola amphi- 
bius of Europe, and, in our country, only surpassed by the muskrat. Its whole 
structure, but particularly its feet and ears, point to its amphibious nature. 
Several specimens in the present collection, from unsuspected localities, enable 
us to greatly extend its known range. Several were taken in Kansas by Mr. 
B. F. Goss, who also forwarded from the same locality in that State (Neosho 
Falls) examples of Onychomys leucogaster, Pedomys austerus, Synaptomys 
coopert, and other interesting animals. These Kansas specimens of Oryzo- 
mys are larger than Carolina or Georgia ones, and otherwise a little differ- 
ent in having heavier tails, lighter colors, &c.; but do not raise a suspicion 
of specific distinction.* 
The original Mus palustris of Harlan purports to be from New Jersey ; 
and, as there is no reasonable doubt of this, it is the northernmost recorded 
locality. There is little to be said of the bibliography of the species; in 
fact, the ‘General Remarks” in Audubon and Bachman, which are here repro- 
duced to settle the question of Mus palustris, Harlan, comprise everything 
essential. ‘We obtained,” they say (op. cit. 216), “specimens of Arvicola 
oryzivora in the winter of 1816, but did not describe it until May 1836... . 
Having occasion to send descriptions of several, then undescribed, species to 
the Academy of Natural Sciences of Philadelphia, we sent a specimen of 
this animal to Dr. Pickrrine, requesting him and Dr. Harlan to compare it 
with the Arvicola riparius of Orv. . . . In searching in the Academy, a speci- 
men of this species was found, and Dr. Haruay, in opposition to the views 
of Pickerine, felt himself authorized to publish it in Sittman’s American 
* A specimen, No. 9436, from Tuchitan, Tehuantepec (Professor Swmichrast), I cannot distinguish 
from the ordinary palustris of Carolina. It is about 4.25 long; tail, 4.50; foot, 1.20. In color, it isa 
little clearer than most Carolina skins, yet not of the paler yellowish-brown noticed in Kansas ones, but 
rather a brighter fulvous-brown; the under parts are unusually pure white. I have not met with any 
Mexican quotations of Oryzomys; but if any species has been described from Mexico, and of which No. 
9436 is an example, it cannot well prove different from palustris. The case seems to me to be parallel 
with that of the Sigmodons elsewhere discussed. 
Two Jamaican skins of Oryzomys (Nos. 7775 and 8117), received since the preceding was written, 
agree completely with palustris in size and shape, but are noticeably different in color. They are of a 
rich ferrugineous-brown, only a little darker along the back, and the under parts are strongly washed 
with a dilution of the same. The difference, indeed, from the ordinary dark Carolina palustris, is nearly 
as evident as in some of the dullest Hesperomys aureolus compared with leucopus. Probably these speci- 
mens represent a race if not a good species; but, in my ignorance of the physico-geographical influences 
that work upon the West Indian rats, I cannot pursue the subject, and especially refrain from giving any 
name to the animal, as I presume it has been described, though I have not met with any reference to it. 
