134 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 97 
shows that his guyannensis specimens have the formula of the dental 
pattern s3 264. Allen’s boimensis and kermiti belong here too, 
according to the pattern of their molariform teeth. P. leucomystax 
is also a member of this group, though the published figures of the 
upper and lower jaws of the type are not sufficiently clear to 
permit an exact determination of the dental pattern. The type 
specimen of elassops Osgood, described from Santo Domingo, Rio 
Inambari, Peru, as a subspecies of P. hendeei shows the cranial and 
dental characters of this group of P. guyannensis. Throughout this 
geographical group there is a strong tendency for retention, to a greater 
or lesser degree, of the fourth fold in the third and often in the second 
upper molars. In all such cases the lower premolar has four folds. 
This pattern is very common among the Central American Pro- 
echimys, and it is questionable whether the name guyannensis should 
apply to them. Other Central American and Amazonian spiny rats 
show the complete quadruplicate pattern in the upper molariform 
teeth and cannot be included in this group. Nevertheless, these 
may have been regarded, in some cases, as “‘topotypes’’ of described 
forms of the group of guyannensis in question. As is shown, two and 
even three species of spiny rats may be found in the same habitat. 
Pending a revision of the genus, it is recommended that the above- 
named forms be treated as subspecies of P. guyannensis. 
The forms of guyannensis (composite) collected by the author in 
northern Colombia represent the two principal dental types that 
follow geographical lines. 
PROECHIMYS GUYANNENSIS MINCAE (Allen) 
Echimys mincae ALLEN, Bull. Amer. Mus, Nat. Hist., vol. 12, p. 198, 1899. 
Type locality—Minca, near Santa Marta, Magdalena, Colombia. 
Distribution.—Base and lower levels of the Sierra Nevada de Santa 
Marta, from near sea level to approximately 500 meters above, De- 
partment of Magdalena, Colombia. 
Characters.—Palest of the Colombian and Central American races 
of guyannensis; color as in guairae and ochraceus of the Venezuelan 
coast, feet whitish, underparts white with or without a gray gular 
band or patch. Formula of enamel pattern of molariform teeth as in 
northeastern South American guyannensis, 335. 
Remarks.—Allen recorded 87 specimens of mincae from Minca and 
Bonda. At the same time he described P. canicollis from specimens 
taken at Bonda, Santa Marta, Mamatoco, and other nearby points, 
all situated on the northwestern foot and base of the Sierra Nevada. 
Apparently, in that region, the two species occur in the same general 
area, if not in the same habitat. The present author took one adult 
