CALUROMYS. 9 
3. Caluromys. 
Se eM — 0. 
Soa Sr 3 
Caluromys Allen, Bull. Am. Mus. Nat. Hist., 1900, p. 189. Type 
Didelphis! philander Linneus. 
Size medium; pouch rudimentary; second hind toe shortest, fourth 
longest, third and fifth equal; fur thick, woolly. Skull with post- 
orbital processes well developed; median crest absent; palate without 
large vacuities posteriorly. 
KEY TO SPECIES AND SUBSPECIES. 
PAGE 
Mumrader parts Yellowish. ..........-..2.1--225802- C. alstont 9 
B. Under parts grayish white. 
IER Ath USE 2... cas 0 ke oe ene C. derbianus 0) 
t& Upper parts pale rufous............. C. lanigera pallidus to 
9. alstoni (Caluromys), Allen, Bull. Am. Mus. Nat. Hist., x11, 
1900, p. 189. 
cinerea Alston, Biol. Centr. Amer., Mamm., 1880, p. 199, pl. XXI. 
(nec Temm.) 
ALSTON’s Opossum. 
Type locality. Tres Rios, Costa Rica. 
Geogr. Distr. Costa Rica, Central America. 
Color. Above sooty, the hairs tipped with deep chestnut brown; 
under parts yellowish; space from nose to crown between eyes buff, 
inclined to reddish on top of nose; two blackish streaks on side of 
nose to and encircling eyes; cheeks and upper part of throat buff; 
ears naked, brown; hands reddish brown; feet yellowish; tail covered 
with hairs colored like back at base for about 37 mm., naked and 
yellowish for the rest of its length. 
Measurements. Total length, 430; tail, 250; hind foot to claws, 25. 
Skull: occipito-nasal length, 43; Hensel, 42; zygomatic width, 23.5; 
interorbital constriction, 7; length of nasals, 11.5. 
10. *derbianus (Didelphys), Waterh., Jard., Nat. Libr., Mamm., x1, 
1841, p. 97- 
Ear OF DEerRBy’s Opossum. Native name Chucha Rata. 
Type locality. Unknown. 
* There is considerable variation in the markings of this species, the dorsal 
stripe being much more restricted in some specimens than in others, and one 
example, No. 11,788, Collection of the New York Museum, is almost uniform 
sooty above tinged with reddish, and the tips of the hairs whitish. The gray 
between the shoulders is indistinct and mixed with the general color, and not in 
a stripe, while the head above is sooty in the center, and reddish brown on 
sides of occiput and also on the neck. There is none of the rust color, so con- 
spicuous on the typical style, anywhere visible. 
