1893-] Allen and Chapman on Trinidad Mammals. 217 



color above varies from strong clear yellowish brown to a darker 

 shade, approaching yellowish chestnut. Below the color varies 

 from pale buffy gray to quite strong buff over the middle of the 

 ventral surface, fading to lighter on the throat and towards the 

 anal region. This variation is, however, mainly due apparently 

 to age, the younger adults being more buffy below and yellower 

 above. The young, as already described, are dusky brown, with 

 a faint wash of pale yellowish brown. 



This species is very distinct from either of the preceding, both 

 in external and cranial characters. Its heavy, comparatively 

 coarse pelage gives it almost an Arvicoline appearance, v hich its 

 relatively smaller ears and shorter tail tend to heighten. In cra- 

 nial characters it most nearly approaches O. palustris of any of 

 the species here described, particularly in the form of the lower 

 jaw, which has the coronoid process longer and more decurved, 

 and the posterior border of the mandible more deeply hollowed 

 than is the case in any of the others. It differs from O. palustris 

 in the form of the interparietal, through its great transverse 

 breadth as compared with its antero-posterior extent ; in this 

 respect essentially agreeing .with the preceding species, as it does 

 also in the comparatively slight development of the supra- 

 orbital ridges. 



This was apparently the most abundant Rodent near the rest- 

 house. With O. spcciosus and O. trinitatis it was found in the 

 dense, low growth which bordered small streams. 



17. Abrothrix caliginosus ( Tomes}. A series of 1 1 speci- 

 mens of a short-tailed, Arvicola-\\ke, rich chestnut-colored mouse 

 is provisionally referred to this species. They agree with a 

 single specimen from Costa Rica provisionally identified with 

 this species, 1 and with Tomes's description of caliginosus. As, 

 however, the type locality of caliginosus is Ecuador, it seems 

 probable that a comparison of specimens from the two localities 

 will show that the Trinidad animal may be separable. 



The coloration above is dark rusty chestnut finely punctated 

 with black, much paler and more yellowish below ; ears, tail, and 

 feet black. A series of six adults, measured before skinning, 



1 See this Bulletin, III, 1891, p. 210. 



