54 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 69 



genus in the well-developed postorbital processes, trje arcuate instead 

 of straight and anteriorly much-converged maxillary toothrows, and 

 in important dental details. 



PHILANDER LANIGER DERBIANUS Waterhouse 



Derby's Woolly Opossum 



Didelphys derbianus Waterhouse, Jardine's Naturalist's Library, Mamra., 

 Vol. XI, p. 97, 1841. Type region, Cauca Valley, Colombia. 1 



The beautiful woolly opossums of the Philander laniger group are 

 distributed throughout much of South America and range northward 

 to southern Mexico. Their more ornate appearance, as compared 

 with the other opossums of the region, has already been indicated in 

 the remarks on the genus. 



The specimens from eastern Panama agree fairly well with descrip- 

 tions and are assumed to represent P. I. derbianus which seems to be 

 distinguishable among the subspecies credited to the republic by its 

 rich cinnamon rufescent coloration. This form has a distinct grayish 

 stripe several inches in length on the median line between the 

 shoulders sometimes referred to as the " withers mark." 



Derby's opossum appears to be less numerous than the other large 

 species of the region, but this apparent scarcity may be partly due to 

 more arboreal habits. None were caught in traps set on or near the 

 ground where the other species were readily taken. At Cana a speci- 

 men obtained by using the hunting lamp at night was located in a 

 tall forest tree by the glare of its eyes in the restricted field of light. 

 At Tabernilla one was discovered in a nest of leaves placed in a 

 tangled mass of vines in the top of a small tree near the edge of the 

 forest. The localities show that P. I. derbianus ascends from sea 

 level to at least 1,800 feet altitude on the slopes of the mountains*. 



Alston (1879, p. 199) noted a specimen in the British Museum 

 obtained by Arce at Chepo. 



Specimens examined : Cana, I ; Tabernilla, I. 



PHILANDER LANIGER PALLIDUS Thomas 

 Pale Woolly Opossum 

 Philander laniger pallidas Thomas, Ann. Mag. Nat. Hist., Ser. 7, Vol. 4, 

 p. 286, October, 1899. Type from Bugaba, Chiriqui, Panama (altitude 

 800 feet). 



As Thomas (/. c.) remarks, " This appears to be a pale inornate 

 race of the ordinary brightly marked Ph. I. derbianus." Although 

 somewhat variable, some specimens approaching P. I. derbianus, the 

 general color is paler and the markings less distinct than in that form. 



1 As restricted by Allen (1904, p. 57) and Thomas (1913, p. 358). 



