I40 Field Museum of Natural History — Zoology, Vol. X. 



whole Bogota region and, as in the case of C. gcmdotii, it may mean that 

 the specimen actually had its source in the savannas east of Bogota 

 near the Meta River. Pucheran's figure, however, shows a pair of 

 horns of somewhat unusual character, not referable with certainty to 

 any known species. The disposition of the name columbicus, therefore, 

 awaits competent examination of the tjrpe in the Paris Museum. 



Rhipidomys fulviventer elatturus subsp. nov. 



Type from Paramo de Tama, head of Tachira River, Venezuela. 

 Alt. 7,000 ft. No. 1 8691 Field Museum of Natural History. Adult 

 male. Collected March 3, 1911, by W. H. Osgood and S. G. Jewett. 

 Original No. 4252. 



Characters. — X small Rhipidomys, smaller than any pre\4ously 

 described species of the restricted genus; general characters and colora- 

 tion essentially as in R. fulviventer, but belly paler, tail shorter, hind 

 foot smaller, and audita! bullae smaller. Upper parts practically 

 uniform ta^^^ly ochraceous evenly and finely mixed with dusW; a 

 slight ta^^Tiy ochraceous line; ears and tail sooty brown; under 

 parts creamy white, lightly washed on the middle of the belly 

 with pale tawny, the hairs, except those of the chin, with dark slaty 

 bases. 



Measurements. — Type and adult female topotype, respectively: 

 Total length 225, 225; head and body 108, 108; tail 117, 117; hind foot, 

 with claw 24, 23. Skull of type: Greatest length 28.2; basilar length 

 21.4; zygomatic breadth 15.6; interorbital constriction 4.3; nasals 11.3X 

 2.9; interparietal 10.7x3.9; palatine foramina 5.7x2; diastema 7.4; 

 upper toothrow 4.5. 



Remarks. — This form is well distinguished from fulviventer but in 

 the present unre vised condition of the genus, its relationship is con- 

 veniently indicated by the trinomial. Typical examples of fulviventer 

 have not been available for use in the present connection and con- 

 clusions have been based upon the original description supplemented 

 by specimens from eastern Peru referred to fulviventer by Oldfield 

 Thomas. 



It is not improbable that the rats of this genus are more restricted 

 within the boundaries of continuously forested areas than those less 

 arboreal in habit. Relatively small discontinuities of forest, therefore, 

 may be locally more effective factors of isolation than temperature 

 and altitude. 



