90 bulletin: museum of comparative zoology. 



only be separated by the slightly larger, wider, and longer palatal foramina and 

 rather heavier molars. The nasals are pointed posteriorly as in that form, by 

 which character the skull can be distinguished from that of P. centralis clii- 

 riquinus Thomas or P. burrus Bangs. The rostrum is rather heavy, less de- 

 curved, and rather straighter than in pananiensis. 



Color and Pelage. — Spines confined to anterior two- thirds of back, not very 

 numerous and rather softer than in allied forms ; colors very dark : upper parts 

 burnt umber, most of the hairs as well as the spines tipped with black ; head, 

 tup of nose, and cheeks chiefly blackish, slightly varied with Vandyke brown ; 

 sides a little paler than back and with fewer black tips to the hairs ; under 

 parts white only along middle of belly, the under surface of legs, arms, neck, 

 anal region, and sides of belly being dull mars brown or russet ; upper surface 

 of feet and hands brownish black ; tail Idack above, dull gray below, well 

 clothed with short, stiff hairs ; ears black. Young similar to adults, but still 

 darker, having a pronounced black dorsal band. 



Measurements — 



Skull. — Type, old adult ^i Basal length, 59 ; occipito-nasal length, 65 ; 

 zygomatic width, 30.4 ; mastoid width, 23.8 ; least interorbital width, 13 ; length 

 of nasals, 25; width of nasals, 7.2; length of palate to palatal notch, 22.6; 

 length of palatal foramina, 5.8; upper tooth row, 10.2 ; length of single half 

 of mandible, 35.4 ; lower tooth row, 10.2. 



Remarks. — The spiny rat was not uncommon in Gorgona Island, and a much 

 larger number were trapped than could be preserved, as the crabs ate them up 

 as soon as caught. 



The form is very well marked, so far as color goes, in its blackish uj^per parts 

 and the small amount of white on the belly, being very different from the other 

 forms of this group, all of which are reddish brown above and pure white below. 

 The skull, however, does not appear to differ markedly from that of P. centra- 

 lis panamensis^ which is probably the nearest all}- of the present island form. 



DASYPROCTIDAE. 



2. Dasyprocta variegata Tschudi. 



One young $. This specimen is unfortunately too young to identify posi- 

 tively, but it seems to belong to this species. 



1 Tip of tail gone. 



