8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 66 



Remarks. — Though resembUng Brotomys in its general features 

 the genus Boromys seems well characterized by the'presence of the 

 supplemental groove at base of antorbital foramen. Whether the 

 teeth are actually as dififerent from those of Brotomys as they appear 

 must remain an open question until young individuals of both genera 

 have been procured. That the patterns will prove to be identical 

 seems improbable. In Boromys the median outer and median inner 

 loops, corresponding to those present in Brotomys, are more deeply 

 sunk into the crowns than the others ; hence it is evident that a stage 

 of wear would later be reached at which the structure in the two 

 animals would be the same. But apparently at that stage the crowns 

 of the teeth would be longer and less nearly terete in Boromys than 

 in Brotomys. In reaching it a different course would be followed. 

 The lake representing the antero-external loop in Boromys is larger 

 and deeper than that representing the postero-internal loop, so that 

 it remains well developed after the latter has disappeared. In 

 Brotomys the only trace of a lake is in a position behind the median 

 external loop and exactly opposite the tip of the median internal 

 loop, therefore not in the place where the last remnant of a postero- 

 internal loop should occur. 



The enamel pattern of Boromys is identical with that of Sticliomys. 

 As compared with the Santa Cruzian genus the Cuban animal differs 

 (a) in the more forward position of the zygomatic root relatively 

 to the maxillo-premaxillary suture and the toothrow, (b) in the 

 apparent shortness of the rostrum which results from this peculiarity 

 of the zygoma, and (c) in the narrower palate (width of palate at 

 pm* scarcely greater than that of alveoli). The concavity on pos- 

 terior border of zygomatic root extends slightly beyond level of 

 anterior surface of pm*, Avhile in Sticliomys its most anterior portion 

 is a little behind level of middle of this tooth. 



BOROMYS OFFELLA, sp. nov. 



Type. — Anterior half of skull (lacking the nasal bones, interorbital 

 region and posterior termination of palate), No. 21 7138, U. S. 

 National Museum. Collected in village site at ]\Iaisi, Baracoa, Cuba, 

 by M. R. Harrington. Presented by George G. Heye. 



Characters. — As in the genus ; measurements : from front of incisor 

 to back of m^ (alveoli), 29.2; palatal breadth including alveoli of 

 second molars, 9.0; least breadth of palate between premolars, 3.0; 

 rostral breadth across nasal rim of premaxillaries, 8.2; depth at 



