550 Mr. O. Thomas on new 
Fab. Puno, Peru, alt. 4000 metres. 
Type: B.M. no. 97. 10. 3. 33. Coll. J. Kalinowski, 
June 15, 1896. 
Of this wonderful and uniquely coloured mouse Mr. Kali- 
nowski fortunately obtained three specimens. Had there 
been only one it might have been supposed to be partially 
albinistic. 
Mr. Kalinowski also obtained in the same district examples 
of Phyllotis boliviensis, Waterh., Retthrodon pictus, 'Thos., 
and Ctenomys opimus, Wagn. Neither Phyllotis nor Ctenomys 
had been previously recorded from Peru. 
Echimys gymnurus, sp. n. 
Size about as in FH. semdspinosus. Pelage much less 
uniform in character than in the allied species, the spines, 
owing to their unusual thickness and length, contrasting 
markedly with the hairs, not only to the touch, but to the 
sight; spines uniformly distributed over the whole of the 
upper surface, though longer and stronger on the back. 
General colour deep rich ferruginous, lined with black, and 
much broken on the back by the black ends of the dorsal 
spines; the hairs throughout are dull slaty basally, with 
bright ferruginous tips. Spines of the central back about 
29 or 80 millim. in length by 2 millim. in breadth at the 
broadest part near the base, whence they taper evenly to the 
strong sharp point; in colour they are white for their basal 
and black for their terminal halves, but on the sides there is 
a subterminal dusky band, succeeded by a pale reddish tip. 
Head rather darker than body, the mixture of black and 
rufous finer. Under surface sharply defined, white from chin 
to anus, the dark colour approximating a little on each side 
under the throat. Forearms and upper surface of hands 
brown, digits almost naked. Legs brown; metatarsals and 
digits very thinly covered with silvery hairs. ‘Tail practi- 
cally naked, the few finer hairs imperceptible without a lens, 
the scales large and prominent; upper surface grey, lower 
white. 
Skull very rugged, with strongly marked ridges and crests ; 
muzzle long and narrow. Nasals long, evenly tapering back- 
wards, their hinder edges obliquely truncated, their line of 
truncation continuous with the oblique hinder edge of the 
premaxillary processes ; their tip just level with the ascending 
zygomatic root. Supraorbital ridges evenly and widely 
curving outwards, then converging again across the parietals, 
along which they run as single distinct ridges nearly to the 
outer corners of the interparietal. Ascending root of zygoma 
excessively slender when viewed laterally, though more than 
