new Neotropical Mammals. 251 
the interparietals. Palatal foramina short, not nearly reach- 
ing tothe molars. Posterior nares wide, though not so wide 
as in N. russulus. Incisors broad and powerful. Molars 
broad and short, their structure as in the allied species. 
Dimensions of the type (measured in the flesh) :— 
Head and body 141 millim.; tail 149; hind foot, s. u. 33, 
c. u. 86; ear 15. 
Skull: greatest length 34; basilar length 27; greatest 
breadth 18:2; nasals, length 14, greatest breadth 3°8, breadth 
at half their length 2-1; interorbital breadth 5:9; inter- 
parietals 2°9 x 8; palate length 16°5; diastema 10; palatal 
foramina 5:4; length of upper molar series 5:3. 
Hab. St. Javier, Hsmeraldas Prov., N.W. Ecuador. Alti- 
tude 20 m. 
Type. Male. B.M. no. 1. 3.19.8. Collected 11th July, 
1900. Three specimens examined. 
This is a most interesting species, as forming with JV. rus- 
sulus a special group less adapted for an aquatic life than the 
typical Nectomys. Like that species, it has a very Oryzomys- 
like general appearance, and might easily be supposed to be 
a member of that genus if the skull were not examined. 
Allen’s Sigmodontomys alfarot is also probably a member of 
the same group. 
N. esmeraldarum is very readily distinguishable both from 
N. russulus and Dr. Allen’s alfarot by its smaller size, more 
broadly ridged skull, and different colour. Its unusually 
narrow nasals may perhaps prove to be abnormal, as a 
younger specimen than the type has them already slightly 
broader. 
Oryzomys tectus, sp. n. 
A large species with a general resemblance to the O. flavi- 
cans group, but brighter-coloured and with remarkably ex- 
panded supraorbital ridges. 
Size fairly large. Fur long, close, straight, and crisp; 
hairs of back about 13 millim. in length and very uniform. 
General colour above rich uniform tawny fulvous, but little 
lined with black. Sides brighter and more ochraceous. 
Face duller and greyer mesially, the upper lips fulvous. 
Ears short, rounded, a tuft of ochraceous hairs behind their 
posterior bases. Chin white, the hairs white to their bases. 
Rest of under surface buffy, continuous with but paler than 
the colour of the sides; the hairs everywhere slaty basally. 
Upper surface of hands and feet pale buffy; palms and soles 
flesh-coloured. Tail of average length, finely and thinly 
