NORTH AMERICA AND THE WEST INDIES 125 



with these, Anthony insists that they resemble agoutis rather 

 than spiny rats and would even make a separate subfamily, 

 Heteropsomyinae, for their inclusion. 



Hitherto these genera have not been found in any of the 

 West Indies except Puerto Rico. 



Family HEPTAXODONTIDAE 



HEPTAXODON BIDENS Anthony 



Heptaxodon bidens Anthony, Bull. Amer. Mus. Nat. Hist., vol. 37, p. 183, Jan. 29, 



1917 ("Cave . . . near Utuado, Porto Rico"). 

 FIGS.: Anthony, 1917a, pi. 5, figs. 1-6 (palate, jaw, teeth). 



This must have been a remarkable hystricomorph, and it 

 adds another to the peculiar mammals of this type known from 

 Puerto Rico. It is known only from fragments of the jaws 

 secured in cave excavation at Utuado and near Morovis and 

 Ciales and hence was probably well distributed in the forested 

 parts of the island at no very distant period. Its few remains 

 seem to have occurred in much the same manner as those of 

 other mammals in these deposits; hence it may be assumed 

 that it lived up till about the time of discovery by whites. 



Of about the size of a woodchuck, this animal was notable 

 not only for the laminated pattern of its upper and lower 

 grinding teeth, but also for the fact that these seem to have 

 been reduced to but two in each series. The upper premolar 

 was of seven "distinct and separate parallel laminae of strong 

 enamel . . . oblique to the main axis of the toothrow," 

 while the lower premolar was similar but reversed. In the form- 

 er, however, the last enamel space is not quite completely cut 

 off from the one in front. In the type fragment a space is 

 present for a molar, and the palatal notch extends forward to 

 the level of the hind margin of the premolar. In a lower 

 mandible there are apparently only the premolar and first 

 molar present. The length of the premolar is 11.5 mm. 



According to Dr. Anthony, its discoverer, the affinities of 

 Heptaxodon are with the Puerto Rican Elasmodontomys, but 

 on the other hand it is so different that both may be regarded 

 as representing distinct subfamilies of the Chinchillidae, or it 

 may be relegated to a distinct family of its own (Miller and 

 Gidley). What relationship if any it may have to the genera 

 discovered by the same investigator in Jamaica, and named 



