ALLEN: FOSSIL MAMMALS FROM CUBA. 139 



length of the skull. As in Capromys, the mastoid and styloid processes 

 are slender but well developed, though damaged in the specimen. 

 Among the many fragments of crania and lower jaws are two rami 

 containing all the teeth, and so supplying the characters of the last 

 lower molar, which, in my previous paper, I was unable to give. As 

 there shown, it is the premolar only that has a secondary re-entrant 

 loop of enamel in the anterior half of the crown. In all three lower 

 molars, the enamel-pattern is essentially similar, and consists of an 

 outer and an inner median fold, the tip of the former ending slightly 

 behind that of the latter; in the posterior half of the crown is a 

 secondary shallower re-entrant from the inner side, that becomes cut 

 off b}- wear to form a small round enamel-lake, and then by further 

 wear disappears altogether. In Boromys torrci, the last lower molar 

 differs from the two preceding in its reduced crown-area and in the 

 proportionally greater length of the main inner re-entrant, which 

 extends nearly to the opposite side of the tooth. The general char- 

 acter of the tooth-pattern shows much resemblance to that of the less 

 specialized types of spiny-rats (Echimys) and even to that of Thry- 

 onomys. The form of the skull, however, is very different in its short 

 rostrum, weak teeth, large bullae and full, rounded brain-case, sug- 

 gestive of a tree-living animal. 



The skull measures: — greatest length 42.5 mm.; basal length 33.4; 

 palatal length 17; diastema 9.5; zygomatic width 23; mastoid width 

 18.5; least interorbital width 11; upper cheek-teeth (crowns) 7.2; 

 lower cheek-teeth (crowns) 7; lower diastema 5. 



Sundry associated limb-bones are taken, to be those of this species, 

 and indicate a relatively short-legged animal with separate tibia and 

 fibula as in Echimys, Capromys, Thryonomys. 



In addition to the series of specimens from Sierra de Hato Nuevo, 

 Messrs. W. S. Brooks and Goodwin Warner obtained this species also 

 in recent cave-deposits from Sierra de Casas, Isle of Pines, indicating 

 that its distribution formerly included that island as well. Peterson 

 (1917) has lately published the finding of five "skulls and portions of 

 skulls" in a cave on this island by the Messrs. Link in 1913. 



Boromys offella Miller. 

 Plate 1, fig. 6. 



Boromys offella Miller, Smithsonian misc. coll., 1916, 66, no. 12, p. 8. 



This larger species of Boromys was based on the anterior half of a 

 cranium from the Indian village-site at Maisi, Baracoa, Cuba. The 



