640 THE AMERICAN NATURALIST. (Vor. XXXV. 
Remarks. — This island species of Loncheres belongs to a 
group quite different from either true Loncheres or Isothrix. 
The skull is, in important characters, similar to that of true 
Loncheres, but the pelage is very different in wholly lacking 
spines. Isothrix has still softer pelage and more hairy tail, 
and also a different skull. I hope some mammalogist, with 
more material at his command than I now have, will before 
long readjust and properly divide the different groups of this 
series of “ spiny rats." 
Loncheres labilis was abundant in San Miguel Island, but 
was wholly arboreal,' Mr. Brown catching all his specimens in 
traps set on the branches of large trees. It appears to be 
diurnal, and on one or two occasions Mr. Brown saw the 
animal proceeding along the branches with a curious gliding . 
gait, his account suggesting the name I have used for the 
species. It is the “Raton Marenero”’ of the islanders. 
Proechimys burrus! sp. nov. 
Fifty-one specimens, April and May. 
Type: No. 8458, adult 3, Bangs Collection, Museum of 
Comparative Zoólogy. Collected April 30, 1900. 
Characters: A large, bright-colored, insular form of the 
Proechimys centralis series. Differing from its nearest main- 
land ally, P. centralis panamensis Thomas, by its larger size 
and richer red color. 
From P. centralis chiriquinus Thomas it differs in less spiny 
back and redder colors. In color it is nearest to P. centralis 
centralis (Thomas), but its feet are much darker. 
The skull is slightly different from that of any of the other 
subspecies. The rostrum is heavier, even, than in chiriquanus. 
The nasals are long, broad, and bluntly truncate posteriorly. 
(In centralis and panamensis the nasals are pointed posteri- 
orly, and in chiriguinus they are shorter and less bluntly 
truncate.) Hamular process broad and spatulate, as in the 
other subspecies. Palatal foramina shorter than in chirigui- 
nus, and less parallel-sided and wider open than in centralis 
and panamensis, 
1 Burrus, red, rufous. 
