l8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



Two toothless mandibles, not improbably pertaining to one indi- 

 vidual, dug from the small available area of original floor material in 

 the caved-in chamber near St. Michel, are unique, among the octodont 

 rodents which I have examined, in the presence of a well developed 

 fifth alveolus behind the normal fourth (pi. 2, fig. 46). 



PLAGIODONTIA ^DIUM F. Cuvier 



Seven mandibles (five from the group of caves near St. Michel, 

 the others from the crooked cave near I'Atalaye) are referable to the 

 species represented by the large specimen from San Pedro de Macoris, 

 Dominican Republic, which I have identified (Proc. U. S. Nat. Mus.. 

 Vol. yz. Art. 16, pp. 5-6, September 30, 1927) as an individual of 

 the species originally described by F. Cuvier. Only one of the Haitian 

 specimens is fully adult, and in this the coronoid and angular regions 

 are broken ofif and all the teeth have been lost. Its size must have been 

 almost exactly the same as that of the Macoris jaw. In each the length 

 of the symphysis menti is 27.6 mm. and the distance from the posterior 

 angle of the symphysis to anterior margin of alveolus of pm^ is 20.4. 

 Among 13 jaws of the recently described Dominican Plagiodontia 

 hylccuui Miller the maxima for these two measurements are only 25.4 

 and 19.0, while the usual dimensions in adults are decidedly less, about 

 24 and 17. The length of the toothrow in the adult Haitian P. (rdium, 

 23.4, is only 0.6 mm. less than that in the Macoris specimen ; the 

 maximum in the series of P. hylceuni is 20.6. In two of the younger 

 Haitian individuals, both of them broken off immediately behind the 

 toothrow, the second molar is not yet fully in place. They are, how- 

 ever, distinctly larger and more robust than in two jaws of immature 

 Dominican P. hyhrmu, one with m^ worn fiat but j;;^ not in place, the 

 other with all the crowns worn flat. In the five Haitian specimens 

 with teeth the enamel pattern presents the characters which distinguish 

 Plagiodontia cedium from P. hylcciim (see Miller, Proc. U. S. Nat. 

 Mus., Vol. y2, art. 16, p. 4, and pi. i, figs, ic and 2, September 30, 

 1927). 



PLAGIODONTIA SPELiEUM sp. nov. 



Type. — Right mandible of young adult. No. 253160, U. S. Nat. 

 Mus. Collected in the crooked cave near the Atalaye plantation, Haiti, 

 March, 1925, by Gerrit S. Miller, Jr. 



Characters. — Resembling Plagiodontia liyhcitui Miller from eastern 

 Dominican Republic but noticeably smaller; length of mandible mea- 

 sured from articular process probably not much exceeding 40 muL 



