CALUROMYS. 9 



3. t'aliiroiuys. 



iJ: c.S; Pf; M.J=J = 50. 



Caluromys Allen, Bull. Am. Mus. Nat. Hist., 1900, p. 189. Type 



Didelphis! philander Linnaeus. 



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. 



PAG n. 



A. Under parts yellowish C. alstoni 9 



B. Under parts grayish white. 



a. Upper parts rusty C. derbianus 9 



b. Upper parts pale rufous C. lanigera pallidus 10 



9. alstoni (Caluromys}, Allen, Bull. Am. Mus. Nat. Hist., xm, 



1900, p. 189. 



cinerea Alston, Biol. Centr. Amer., Mamm., 1880, p. 199, pi. xxi. 



(nee 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., xi, 



1841, p. 97. 



EARL OF DERBY'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. 



