20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 51 



all of the maxillary teeth with two about equally developed reentrant 

 angles on each side, these imparting to the crowns an evenly six-lobed 

 structure (pi. 3, fig. i). 



Remarks. — In the general structure of the palate and the relation- 

 ship of the incisor roots to those of the premolars this genus is prac- 

 tically identical with Gcocapromys. The roots of the premolars come 

 close together in the median line, where they are overgrown by the 

 maxillary exactly as in Gcocapromys. The roots of the premolars 

 with their covering of bone fill up the lower part of the narial channel 

 in the region between the incisor roots (pi. 3. fig, i^). A broken 

 palate without teeth could be distinguished by this character alone 

 from a similar fragment of a Caproiiiys or Plagiodontia skull, in both 

 of which the anterior part of the narial channel is widely open between 

 the roots of the premolars (pi. 3, fig. 2), but might be confused with 

 a similar fragment pertaining to a member of the genera Gcocapromys, 

 Isolohodon, or Apluetrcus. 



In Gcocapromys and Capromys (pi. 3, fig. 2) the roots of all four 

 cheekteeth, when exposed by cutting or breaking away their bony 

 covering, are seen to l)e about evenly spaced in the toothrow — at most 

 the septum between the roots of pm* and m^ is slightly thicker than 

 the septa between the molars. In Hc.volobodon, on the contrary (pi. 3, 

 fig. lb), the root of the premolar is thrown conspicuously forward 

 away from that of the first molar. 



The less si>ecialized condition of the roots of the cheekteeth and 

 the extension of the lower incisor root to the outer side of the 

 mandibular toothrow are characters which, like the enamel jjattern of 

 the upper teeth, sharply difi^erentiate this genus from its Antillean 

 relatives Capromys, Gcocapromys. Plagiodontia, Aphcctrctts, and 

 Isolohodo}}. 



HEXOLOBODON PHENAX sp. nov. 



Plate 3, figs. I, la, ib 



Type. — Palate with complete dentition of immature individual {m^ 

 with only anterior half of crown worn flat). No. 2531 18. U. S. Nat. 

 Mus. Collected in the small cave near St. Michel, March, 1925, by 

 Gerrit S. Miller, Jr. 



Characters. — An animal about the size of Capromys piloridcs, 

 but skull i)robably ditfering from that of all species of Capromys and 

 Gcocapromys in shorter rostrum and generally more robust form. 

 With regard to features which are not obviously generic, such exact 

 comparisons with Capromys piloridcs as the fragmentary remains of 



