Proceedings of the Biological Society of Washington

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1897. Excerpt: ... DEC 21 1BS? Vol. XI, pp. 277-279 December 17, 1897 PROCEEDINGS OF THK BIOLOGICAL SOCIETY OF WASHINGTON NELSONIA NEOTOMODON, A NEW GENUS AND SPECIES OF MURINE RODENT FROM MEXICO. BY C. HART MERRIAM. The collection of mammals made in Mexico by Mr. E. W. Nelson still contains many novelties. Recently, in looking at the skull of a large White-footed Mouse from the mountains of Zacatccas, supposed to be a typical Pcromyscus, I was startled to find that it had the flat-topped prismatic teeth of a Wood Rat, Neotoma. Closer examination of the dentition showed that while the 1st and 2d upper and 1st lower molars agree essentially with those of Neotoma, the 3d upper and 2d and 3d lower differ so materially that it is necessary to erect a new genus for the animal's reception. The skull also is peculiar and unlike either Neotoma or Peromyscus. The most important difference is in the antorbital slit, which does not notch the upper surface of the maxillary root of the zygoma. Another character is the production of the inferior angle of the antorbital slit to form a distinct process. The tail is large and blunt, much as in Neotoma---not tapering to a slender point as in Peromyscus. The new genus may be defined as follows: Nelsonia gen. nov. Type.--Nelsonia neotomodon sp. nov., from Plateado, Zacatecas, Mexico. Diagnosis.--Cranial characters: Skull in general resembling that of a large Pcromyscus but flatter; zygomata heavier, less depressed, and more spreading anteriorly; antorbital slits relatively narrow and only faintly notching upper surface of maxillary root of zygoma; inferior angle of antorbital slit thickened and protruding forward and out ward as a distinct process; audital bulUe sub-conical as in Pcromyscus and Hodumys, not bullate as in Neotoma and Xenomys; b...