46 Bulletin American Museum of Natural History. [Vol. XIV, 



it differs in its relatively somewhat shorter tail and very much 

 smaller ears. Known at present only from the type specimen. 



Oryzomys castaneus, sp. nov. 



^ No. 1-3-19-11, British Museum, $ adult, St. Javier, northern Ecua- 

 dor, altitude 60 feet, July 28, 1900 ; collected by G. Flemming and R. Miketta. 

 Orig. No. 171. 



Similar in texture of pelage and coloration to O. nitidus, but much smaller, 

 with relatively as well as absolutely much weaker dentition. General color 

 above dark reddish brown or light chestnut, paler, more yellowish brown on 

 the sides ; below dull whitish or soiled grayish white, the fur being plumbeous 

 at base and broadly tipped with whitish. Upper surface of fore and hind feet 

 nearly naked, flesh color, palms flesh color, soles dark brown ; ears of medium 

 size, brown ; tail much shorter than head and body, naked, pale brown above, 

 slightly lighter below. 



Measurements (of type and only specimen). Total length, 223 mm. ; head 

 and body, 1 18 ; tail, 105 ; hind foot, 29 ; ear, 19. Skull of the typical form for 

 the genus, with a well-developed supraorbital bead, running back to the parieto- 

 occipital suture ; interparietal large ; posterior palatal opening broad for the size 

 of the skull ; palatal foramina small ; molar dentition weak. Total length, 30 ; 

 basilar length, - ; zygomatic width, 14.4; mastoid width, 11.3 ; postorbital 

 width, 5.3 ; length of nasals, 11.2 ; interparietal, 3X9; length of palate, 7 ; 

 palatal foramina, 4; upper toothrow, 4.1 ; lower jaw, length, 15 ; height at 

 condyle, 7.8 ; lower toothrow, 4.6. 



This species, at present known only from the type, bears a 

 close resemblance in coloration to O. nitidus (Hesperomys lati- 

 ceps, var. nitidus Thomas, type, 85-4-1-41, Br. Mus ), from 

 Amable Maria, Central Peru (P. Z. S., 1884, 452, pi. xlii, fig. i), 

 but is smaller, with a very much shorter and narrower hind foot 

 (27 against 30.5 in O. nitidus, type, both from dry skins), rela- 

 tively shorter tail, and much weaker molar dentition. 



Oryzomys perenensis, sp. nov. 



Tvpe, No. 0-7-7-25, British Museum, $ adult, Perene, Department of 

 Junin, Peru, April u, 1900 ; altitude 800 m. Collected by P. O. Simons ; col- 

 lector's No. 930. 



Very similar in coloration, texture of pelage, size, and proportions to 0. mag- 

 dalenee Allen, but with the skull much broader and the dentition much heavier. 



Measurements (of type). Total length, 237 mm. ; head and body, 125 ; tail, 

 112 ; hind foot, 31; ear, 22. Seven adults range in total length from 227 to 260 

 (one very old male reaches 279) ; length of head and body, from 118 to 135 

 (with one, 144) ; tail length, 105 to 125 (one, 135) ; hind foot, 28-33 ; ear, 

 20-25. 



