138 bulletin: museum of comparative zoology. 



BoROMYS TORREi G. M. Allen. 

 Plate 1, fig. 11-13. 



Boromys torrei G. M. Allen, Bull. M. C. Z., 1917, 61, p. 6, pL, fig. 10-13. 



Boromys was founded by Miller (1916) on the anterior half of a 

 skull excavated in the ancient Indian tillage-site at Maisi, Baracoa, 

 Cuba, and named Boromys offclla. The fragments from Sierra de 

 Hato Nuevo which I described as Boromys torrei, a much smaller 

 species, included but two upper teeth with palate, and all but the last 

 molar of the lower jaw. The later collections of Messrs. Barbour, 

 Brooks, and Warner include numerous jaws of both animals, and a 

 very fine cranium (Plate 1, fig. 11-13), lacking the incisors, of B. torrei. 

 This discovery enables a clearer determination of the characters of 

 the species. The skull is evidently adult, though not aged, since the 

 basioccipital suture is still unclosed. All the teeth are well worn 

 down so that the posterior molar alone retains the enamel lakes left 

 by the wearing away of the secondary re-entrant folds. That this 

 smaller species is really a Boromys and not referable to the Santo 

 Domingan Brotomys is proved by the presence of the supplementary 

 groove at the inner lower corner of the large antorbital foramen, and 

 the pronounced swelling on the inner wall of this part of the maxillary, 

 caused by the root of the upper incisor. The general structure of the 

 skull is much like that of Capromys, but the dorsal profile is more 

 rounded. As in that genus, the parietals and interparietals have 

 fused into a solid plate while the frontals still retain their boundaries 

 distinct. The nasals are lost, but seem to have bowed outwardly at 

 the sides, and to have ended proximally on a level with the entls of 

 the ascending premaxillary branches. The rostrum is short. The 

 incisive foramina open into a broadly excavated pit, the outlines of 

 which are carried back as raised ridges to the inner corner of the first 

 molariform teeth. The small cylindrical cheek-teeth are in two 

 parallel rows, their grinding surfaces bevelled slightly outwartl. The 

 anterior three have worn down below the level of the secondary re- 

 entrant folds of enamel, so that their pattern is that of a figure 8, with 

 the inner re-entrant very slightly in advance of the outer. The last 

 molar is less worn, and contains in the anterior half of its crown, a 

 transversely oval enamel-lake, and in the posterior half a much smaller 

 circular one. The postpalatal portion of the skull comprises about one 

 half its total length. The striking feature is the great proportionate 

 size of the audital bullae, the length of which is a third the basal 



