SIGMODON.—NEOTOMA, 153 
Sailé, Mus. Brit.), Vera Cruz (de Saussure®), Zehuaine, Tehuantepec, Tuxpango, 
Orizaba (Sumichrast, U.S. Nat. Mus.*), Mirador (Sartorius, ib‘); GUATEMALA, 
Duefias (Salvin, Mus. Brit.6); Panama, Veragua (Whitely, Mus. Brit.). 
The Cotton-Rat of the Southern United States and of Central America varies con- 
siderably in colour, and still more strikingly in the proportional length of the tail and 
size of the hind foot, Dr. Coues’s elaborate tables showing a range of from 2'-25 to 
5-25 in the former, and from 0-97 to 1-40 in the latter measurement. Such dif- 
ferences naturally suggest specific distinction; and accordingly they have been the 
foundations of Professor Baird’s® and M. de Saussure’s® species, the extremes in length 
of tail and foot being found in Mexican specimens. But a careful comparison of the 
very large series in the Smithsonian Museum has enabled Dr. Coues to show that every 
intermediate proportion may be found, and that Texan and Mexican individuals differ 
more from each other than they do from Carolina specimens. The examples to which 
IT have access confirm this view, and I therefore fully concur in the identification of 
Sigmodon berlandiert and Hesperomys toltecus with S. hispidus. 
The range of the Cotton-Rat extends further south than has been hitherto recorded ; 
for, though Dr. v. Frantzius does not appear to have met with it in Costa Rica, speci- 
mens have been supplied to the British Museum by Whitely from Veragua. Its habits 
have been fully described by Audubon and Bachman*, who state that it is gregarious 
and highly carnivorous. 
Mr. Salvin’s specimens were obtained at Duefias, and shot in the open at the edge of 
some thick grass; the species, he tells me, is not uncommon in that district. 
5. NEOTOMA. 
Neotoma, Say & Ord, Journ. Acad. Philad. iv. p. 346 (1825). 
In the Wood-Rats we have a typically Nearctic genus, represented in Central 
America by two species, one of which is peculiar to our subregion. Closely allied to 
the last genus, Veotoma has even larger ears and a much longer tail; the skull has 
no supraorbital ridges, and only short incisive foramina; and the molars, except in 
aged individuals, have the indenting enamel-folds open and angular, giving the crowns 
of the teeth very much the prismatic character of those of Arvicola. The genus 
presents two types, according as the tail is densely haired and bushy, as in NV. cinerea 
(Ord) of the western territories, or nearly naked, as in the remaining species. To the 
latter section belong the two forms found within our limits, which differ in the 
following characters :-— 
1. N. floridana. Upper parts greyish brown, washed with fulvous on the flanks ; 
lower parts white ; feet entirely white; tail bicolorous. Average length 9", of 
tail 6”. 
* Quad. N. Am. i. pp. 230-232. 
BIOL. CENT.-AMER., Mamm. Vol. 1, October 1880. x 
