10 billetin: museum of comparative zoology. 



level of the middle of vi^, without the median bony projection found in 

 G. ihorocatiut. 



Measurements. — length of lower diastema of type, 7 mm. ; of pm4, 

 3.1; of till, 3; length of lower molar row in an adult, (9604), 14.3; 

 of pvii, 4; of mi, 3.5; of m^, 3.0; width of mi, in same specimen, 3.7; 

 length of upper molar row (9603), 13.2; distance between tooth rows 

 anteriorly, l.S; posteriorly, D.d; width across anterior corners of 

 alveoli of cheek teeth, 7; width of m^ 3.6. 



Specimens examined. — Five palates with teeth, about 15 jaw frag- 

 ments mostly wath teeth, and numerous other fragments. 



Remarks. — The relationship of the fossil Cuban Geocapromys, 

 seems on the whole to be with G. hrownii in the relatively broad molars 

 with their deep, compressed enamel folds. It is nearer G. ingrahami 

 in size, though even smaller; and further resembles that species in 

 the form of the terminal part of the bony palate, which is arched and 

 lacks the distinct median projection seen in G. thoracatus. The 

 remains of this extinct Cuban species compose most of the original 

 block of bone-breccia which forms the subject of this paper. The 

 bones are so greatly broken, however, that it was impossible to extri- 

 cate any except the dental portions of the skull and a few ear bullae. 



GENERAL REMARKS. 



While it is premature to speculate on the significance of the recently 

 discovered fossil mammals in Cuba, Porto Rico, and San Domingo, 

 it is clear that the additional facts of distribution tend to confirm the 

 evidence for a former continuity of the Greater Antillean land masses. 

 Thus Geocapromys is now known from Little Swan Island, Jamaica, 

 Cuba, and Plana Keys, with probably two types in Jamaica. A Cuban 

 insectivore related to the fossil Nesophontes of Porto Rico parallels 

 the presence of Solenodon on Cuba and San Domingo. Tlje Isolo- 

 bodon of Porto Rico is indistinguishable from that of San Domingo. 

 Related genera of rodents — Brotomys and Boromys — are found 

 to occur in San Domingo and Cuba respectively. These, and other 

 cases among reptiles (Barbour, 1914), birds, and mammals seem to 

 imply a consistent rather than a haphazard method of distribution, 

 the most obvious explanation of which seems to be that the Antillean 

 land mass was formerly of larger extent and that the several islands 

 now representing it were once connected. The dismemberment of 



