APRIL, 1914. MAMMALS OF NORTHERN PERU — Oscoop 169 
Proechimys sp. Spiny Rat. 
Three specimens from Yurimaguas differ decidedly from the large 
series from that locality unquestionably referable to P. brevicauda. 
That they merely represent extreme variation is perhaps not impossible, 
but further collections from the same and the neighboring region may 
show that they belong to another species. They are characterized by 
pure white under parts, like the series from Lagunas, but with very 
long tails, harsh pelage, and largely white hind feet. Two adults 
measure: Total length 388, 366; head and body 220, 213; tail 168, 167; 
hind foot 50, 49. 
Mesomys ecaudatus Wagner. HEDGEHOG Rat. 
Four specimens, Munichis, near Yurimaguas. 
In describing Mesomys stimulax from the Tocantins, Thomas says: 
“This is only the fifth recorded specimen belonging to the rare genus 
Mesomys.”’! The total, therefore, is now increased to nine, of which 
the above small series constitutes nearly half. It is possible that 
comparison of modern material would make it necessary to use for our 
specimens Ginther’s name ferrugineus, the type of which came from the 
same region, but Thomas (Il. c.) has concluded, from comparison of 
Ginther’s old type with specimens from the lower Amazon, that no 
separation is justified. The Yurimaguas specimens show only slightly 
greater measurements than those given for typical ecaudatus and there 
is no appreciable discrepancy in color. The under parts are not quite 
“uniformly buffy”? but the change from the creamy buff of the throat 
and breast to the rich ochraceous buff of the abdominal region is gradual. 
Two of our specimens have perfect tails with long pencils at the tip, a 
third lacks the terminal half of its tail, and the fourth is tailless like the 
original type of ecaudatus. 
Flesh measurements of an adult male are: Total length 412; head 
and body 209; tail 203; hind foot 32. Skull: Greatest length 45.7 
(44); * basilar length 35.1 (33); zygomatic breadth 24 (22.5); nasals 
13.8x 4.8 (12.4x 5); interorbital breadth 11.9 (11); mastoid breadth 
20.7 (20); palatal length 15.2 (15.3); diastema 9.4 (9.9); palatal 
foramina 3.8 (3.8); upper toothrow 7.4 (6.7). 
Mr. Anderson found these rats in the hut he was occupying at the 
small native settlement of Munichis. He was unable to catch them in 
1 Ann. & Mag. Nat. Hist., (8), VII, p. 608, June, rg11. 
* Measurements in parentheses are those given by Thomas for a specimen from 
the lower Amazon. 
