ARBOREAL RICE RATS — HERSHKOVITZ 533 



geographically from its relatives but is not known enough to be 

 characterized. 0. h. occidentalis (new name) of western Ecuador is 

 distinguished by a few trivial cranial characters. 



Oryzomys (Oecomys) bicolor trabeatus G. M. Allen and Barbour 



Oecomys trabeatus G. M. Allen and Barbour, Bull. Mus. Comp. Zoo!., vol. 65, 

 p. 262, 1923.— G. M. Allen, Bull. Mus. Comp. Zool., vol. 71, p. 266, 1931 

 (type history). 



Oecomys endersi Goldman, Journ. Washington Acad. Sci., vol. 23, p. 525, 1933 

 (type locality, Barro Colorado Island, Canal Zone, Panama). — Enders, 

 Bull. Mus. Comp. Zool., vol. 78, p. 454, 1935 (Barro Colorado, Panama; 

 habits). 



Type: Adult male, skin and skull (MCZ 19837) ; collected Apr. 10» 

 1922, by Thomas Barbour and W. S. Brooks. 



Type locality: Rio Jesusito, Darien region, eastern Panama. 



Distribution: Known only from the Canal Zone to the eastern 

 boundary of Panama. The range may extend into Costa Rica on the 

 west and into the Colombian Choc6 on the south; altitudinal range 

 from sea level to about 500 meters above. 



Characters: Those of the species. See "Remarks," below. 



Measurements: Those of the type of trabeatus (from the original 

 description) are followed by those of the type of endersi: head and 

 body, 110, 114; tail, 120, 124; hind foot, 22 (in flesh), 24 (dry); ear, 

 15, 15; greatest length of skull, 26.0, 28.1; zygomatic breadth, 15, 

 15.1; rostrum, — , 5.4; incisive foramina, — , 4.8; diastema, 7.0, 

 7.4; molar row, 4.0, 4.3 (alveolar); width of zygomatic plate, — , 2.5. 



Remarks: Judged by the original description, the type of trabeatus 

 is a young individual of the bright color group. It was compared 

 with three darkly colored individuals of Oryzomys bicolor from eastern 

 Ecuador and said to differ by its "somewhat larger" size, longer tail 

 and longer, thicker pelage. None of these distinctions is valid. 

 Retention here of trabeatus for Central American members of the 

 common species is based solely on the availability of the name and 

 the absence of any records of the occurrence of the species in the 

 deciduous forests of northern Colombia. It is also possible that 

 additional material from Panama may reveal subspecific differences 

 that cannot be accurately evaluated from one specimen. 



The type of endersi Goldman, also from Panama, is an old individual 

 of the dark color group. Its size and color are within the range of 

 variation of the typical form of the species. 



Specimens examined: One (UMMZ, type of endersi, from 

 Panama) . 



Oryzomys {Oecomys') bicolor occidentalis, new name 



Rhipidomys dryas Thomas, Ann. Mag. Nat. Hist., ser. 7, vol. 5, p. 271, 1900 

 (preoccupied by Oryzomys dryas Thomas, Ann. Mag. Nat. Hist., ser. 7, vol. 

 2, p. 267, 1898, a member of the subgenus Microryzomys) 



