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 musk rat. 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 

 cooper/., 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. Pickering, requesting him and Dr. Harlan to compare it 

 with the Arvicola riparius of Ord. . . . In searching in the Academy, a speci- 

 men of this species was found, and Dr. Harlan, in opposition to the views 

 of Pickering, felt himself authorized to publish it in Silliman's American 



* A specimen, No. 9436, from Tuchitau, Tehuantepec (Professor Sumichrast), I cannot distinguish 

 from the ordinary palustris of Carolina. It is about 4.25 long ; tail, 4.50; foot, 1.20. In color, it is a 

 little clearer than most Carolina skins, yet not of the paler yellowish-brown noticed in Kansas ones, but 

 rather a brighter fulvons-brown ; the under parts are unusually pure white. I have not met with any 

 Mexican quotations of Ory:om\js ; but if any species has been described from Mexico, and of which No. 

 94150 is an example, it cannot well prove different from palustris. The case seems to me to be parallel 

 with that of the Sigmodous 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 lnuopus. 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 \\ith any reference to it. 



