104 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 69 



River. It was also taken in smaller numbers in the forest at various 

 elevations up to 2,800 feet on the slopes of the Pirre Range. At the 

 type locality on Cerro Azul it appeared to be rather scarce. Like 

 Nectomys alfari efhcax, Sylvilagus gabbi messorius and other species 

 living on the ground, this rice rat has evidently increased in numbers, 

 locally, with the clearing of the original forest, the new low growth 

 springing up doubtless providing more suitable food and cover than 

 is found in the heavy forest where seed producing undergrowth is 

 largely crowded out. Anthony (1916, p. 369) found the species 

 quite common in the clearing at 2,650 feet at the old village of 

 Tacarcuna, but it seemed rarer at lower elevations and was not taken 

 above 4,200 feet. He records specimens from El Real, Tacarcuna, 

 Maxon Ranch (Rio Trinidad) and Gatun. 



Specimens examined : Cana, 46; Cerro Azul, 1 (type) ; Gatun, 1 l ; 

 Maxon Ranch (Rio Trinidad), 3 1 ; Real de Santa Maria, 2 1 ; 

 Tacarcuna, 23. 1 



ORYZOMYS CALIGINOSUS CHRYSOMELAS Allen 

 Costa Rican Dusky Rice Rat 

 Oryzomys chrysomelas Allen, Bull. Amer. Mus. Nat. Hist., Vol. 9, p. 37, 

 March 11, 1897. Type from Suerre, Costa Rica. 



Under the name Zygodontomys chrysomelas, Bangs (1902, p. 37) 

 noted three specimens of this subspecies collected for him at Bogava 

 by W. W. Brown, Jr. These have been referred by Allen (1904, 

 p. 548) in his revision of the group to Melanomys chrysomelas with 

 the remark that topotypes " agree perfectly with Chiriqui and Nica- 

 ragua specimens of corresponding age." The range of the sub- 

 species is given by him as approximately from Bugaba, Chiriqui, 

 Panama, north to northern Nicaragua. 



Specimens examined : Bogava, 3. 2 



Genus NECTOMYS Peters 

 Members of the genus Nectomys, especially the smaller species, 

 externally resemble some species of Oryzomys. The genus is nearly 

 related to Oryzomys from which it differs notably in rather more 

 hypsodont dentition ; the molar crowns have lower tubercles and the 

 outer reentrant angles are shallower so that with continued wear on 

 the crowns the latter close along the outer side, but remain as deep 

 interior enamel folds or islands which persist to extreme old age, 



1 Collection Amer. Mus. Nat. History. 

 * Collection Mus. Comp. Zool. 



