NO. 5 MAMMALS OF PANAMA GOLDMAN 89 



NYCTOMYS SUMICHRASTI NITELLINUS Bangs 



Chiriqui Vesper Rat 



Nyctomys nitellinus Bangs, Bull. Mus. Comp. Zool., Vol. 39, No. 2, p. 30, 

 text figs. 1 1 -12, April, 1902. Type from Boquete, Chiriqui, Panama 

 (altitude 4,000 feet) . 



Nyctomys sumichrasti nitellinus is comparatively pale and yellow- 

 ish in color above, the general tone decidedly paler than in the allied 

 subspecies, Nyctomys sumichrasti venustulus of Nicaragua and 

 Costa Rica, which differs also in the narrower braincase and posterior 

 part of frontal region. 



The subspecies is based on six specimens obtained by W. W. 

 Brown, Jr., at the type locality. 



Genus RHIPIDOMYS Tschudi. Climbing Mice 

 Rhipidomys is one of those genera found during the present 

 investigations to range within the limits of Panama. Externally 

 the species resembles some forms of Oryzomys ; the tail is very 

 long and clothed with rather long hair ; the hind feet are short with 

 sharp, strongly curved claws adapting the animal for an arboreal 

 life ; cranial examinations are, however, important in order to make 

 accurate generic determinations. The skull of Rhipidomys re- 

 sembles that of Nyctomys in many respects, the braincase being 

 large and the rostrum short and narrow. The frontal region is 

 narrower, however, the incisive foramina much longer than the 

 palatal bridge and reaching posteriorly behind the anterior plane of 

 the first molars. The genus Rhipidomys differs from Nyctomys 

 notably in the form of the anterior upper molar, this tooth bearing 

 six well-developed cusps, while in Nyctomys the anterointernal cusp 

 is less prominent and suggests gradation toward the normally 

 5-tuberculate genus Peromyscus. 



RHIPIDOMYS SCANDENS Goldman 



Mount Pirre Climbing Mouse 



[Plate 23, figs. 4, 4a] 



Rhipidomys scandens Goldman, Smiths. Misc. Coll., Vol. 60, No. 22, p. 8, 

 February 28, 1913. Type from near head of Rio Limon, Mount Pirre, 

 eastern Panama (altitude 5,000 feet). 



The type of Rhipidomys scandens is unique, and no other speci- 

 mens of the genus are known from any part of Middle America. 

 The species is closely allied to R. Venezuela with which it may be 

 expected to intergrade, but until more material is available and the 



