30 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



often in patches, or spots, sometimes occupying nearly the whole of the under 

 surface, sometimes wholly wanting ; and in some specimens the upper surface 

 also is patched with whitish). Very old examples are paler above with the 

 sooty dorsal stripe, less well marked ; younger specimens are darker, often with 

 most of the back sooty. 



Measurements (of ten adults, type and topotypes). — 



Skull, type, adult 9 > basal length, 28.8; occipitonasal length, 32.4; zygo- 

 matic width, 15.6; mastoid width, 13.6; length of nasals, 13; width of 

 nasals, 3.4 ; length of palatal slits, 6.2 ; width of palatal .slits, 3.2 ; length of 

 palate, to palatal notch, 12.8; to end of pterygoid, 19 ; length of upper molar 

 series, 5 ; length of single half of mandible, 17.4. 



Remarks. — Peromyscus cacabatiis was by far the commonest small mammal 

 of the mountain forest belt of the Volcan de Chiriqui. It does not appear to 

 occur below 4,000 feet, and extends from thence upward to the limit of the 

 life zone it occupies, roughly speaking, about 8,000 feet, 7,500 feet is the 

 highest altitude marked on any of the labels. The Mount Chiriqui Peromys- 

 cus, is most nearly allied to P. guatemalensis and P. furvus, but is quite dis- 

 tinct. It is the most southern member of the genus thus far recorded. 



i->^ 



Nyctomys^ nitellinus,^ sp. nov. 



Type. — Mus. Comp. Zo61., No. 10,249, old ad. 9, Boquete, Feb. 8, 1901. 4,000 feet. 



Six specimens, Boquete, 4,000 to 6,000 feet, January, February, and March. 



Characters. — Apparently a very distinct species, though nearest to N. deco- 

 lorus (True) from Rio de las Piedras, Honduras. Color of back, pale and 

 yellowish, but decidedly darker than in N. decolorus. Also larger than N. 

 decolorus ; tail more hairy; skull much larger, with narrower posterior part; 



1 I think all mammalogists must now regard the very well marked Central 

 American hairy-tailed Vesper rats, as generically distinct from Hhipidomys. The 

 important characters are four instead of six mammEe, very slender, short rostrum, 

 exceedingly short palatal slits and peculiarly expanded brain case. The syn- 

 onymy is: Nyctoviys Sauss. 1860; type, N. sumichrasti ; Myoxomys Tomes, 1861; 

 type, M. salvini. 



^ NitelUnus, like a dormouse. 



