98 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 69 



ORYZOMYS ALFAROI DARIENSIS Goldman 



Darien Rice Rat 



[Plate 24, figs. I, la] 



Orysomys alfaroi dariensis Goldman, Proc. Biol. Soc. Washington, Vol. 28, 

 p. 128, June 29, 1915. Type from Cana, eastern Panama (altitude 2,000 

 feet). 



In the richer, more reddish coloration of the upperparts, and 

 usually narrower skull the Darien rice rat differs from the closely 

 allied form, Alf aro's rice rat of western Panama. The Darien animal 

 is rather common in dense thickets at 2,000 to 2,500 feet altitude 

 along- the Cana River, near Cana. The same thickets are also in- 

 habited, apparently in smaller numbers, by O. talamancce. On Mount 

 Tacarcuna an immature example recorded by Anthony ( 1916, p. 368) 

 was secured at 5,200 feet. 



Specimens examined: Cana, 11; Mount Tacarcuna, i.* • 



* 



ORYZOMYS BOMBYCINUS BOMBYCINUS Goldman 



, Silky Rice Rat 



[Plate 24, figs. 3, 3a] 



Orysomys bombycinus Goldman, Smiths. Misc. Coll., Vol. 56, No. ;i6, p. 6, 

 February 19, 1912. Type from Cerro Azul, near headwaters of Chagres 

 River, Panama (altitude 2,500 feet). 



The silky rice rat is a dark-colored, forest-inhabiting species with 

 remarkably long, soft pelage for an Orysomys. It was originally 

 compared with O. carrikeri and O. talamanccs, but is much more 

 nearly related to O. nitidus from Peru, as represented by specimens 

 in the National Museum determined by Mr. Oldfield Thomas. 

 O. bombycinus differs from O. nitidus most noticeably in cranial 

 characters, the braincase being broader, the zygomata more widely 

 spreading posteriorly (zygomata more nearly parallel in nitidus), 

 and the audital bullae larger. 



On Cerro Azul a few of these rice rats were taken in traps placed 

 mainly under logs and about the bases of large forest trees at from 

 2,500 to 3,000 feet elevation near the summit of the mountain. No 

 examples of this species were obtained in the course of extensive 

 field work at the same elevation on the higher mountains near the 

 Colombian frontier. A single individual was taken at about 1,000 

 feet on the forested basal slope of Cerro Brujo where O. talamancce 

 also occurs. 



Specimens examined: Cerro Azul (type locality), 3; Cerro 

 Brujo, I. 



* Collection Amer. Mus. Nat. Hist. 



