90 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 69 



various forms of this unrevised group are better known, it seems 

 preferable to treat the Panama representative of the genus as a dis- 

 tinct species. The upperparts are darker colored than in typical 

 examples of R. Venezuela: and the skull is decidedly broader across 

 the braincase. In the breadth of the braincase it is similar to R. cocal- 

 ensis, another closely related form, but the frontal region is de- 

 pressed anteriorly and much narrower, especially posteriorly, the 

 maxillary arm of the zygoma is heavier, and the interparietal is 

 larger. 



The specimen which became the type was secured just at dusk one 

 evening, when it was seen running rapidly up the trunk of a tree near 

 my camp in the forest, to a point about 35 feet from the ground 

 where the tree was encircled by a mass of Bromeliaceous plants. 

 The mouse paused a moment among the leaves, its long tail hanging 

 straight downward, and was shot. 



Specimens examined: Mount Pirre, 1. 



Genus TYLOMYS Peters 

 The members of the genus Tylomys bear some superficial resem- 

 blance to large examples of Mus rattus. The ears are large and 

 naked, the tail is long and practically bare, the skin of the terminal 

 portion whitish or flesh colored instead of black. The skull is 

 elongated, with low rather flat braincase, and broad frontals which 

 form supraorbital shelves much as in Nyctomys. The outer wall of 

 the antorbital foramen is little developed forward, the anterior 

 border concave. The first upper molar is evenly rectangular with 

 six well-developed tubercles arranged about as in Rhipidomys. 



TYLOMYS PANAMENSIS (Gray) 



Panama Climbing Rat 



Ncomys Panamcnsis Gray, Ann. Mag. Nat. Hist., Ser. 4, Vol. 12, p. 417, 

 November, 1873. Type from Panama. 



The Panama climbing rat was described from a specimen obtained 

 by the British Museum through M. Boucard. To this species I pro- 

 visionally refer three immature specimens with narrow, elongated 

 skulls, taken near Cana. In cranial characters they are much like 

 7". mircc, however, and quite different from a comparably immature 

 example from Cerro Brujo which may represent T. watsoni. 



One of the specimens was taken in a banana-baited trap placed 

 among rocks at 2,000 feet altitude near the entrance to an abandoned 

 tunnel at the Darien gold mines. One caught in a trap set under a 



