Vol. XII, pp. 115-125 April 30, 1898 PROCEEDINGS BIOLOGICAL SOCIETY OF WASHINGTON DESCRIPTIONS OF TWENTY NEW SPECIES AND A NEW SUBGENUS OF PEROMYSCUS FROM MEXICO AND GUATEMALA. BY C. HART MERRIAM. The enormous collection of mice of the genus Peromyscus made in Mexico and Guatemala by Mr. E. W. Nelson and his assistant, Mr. E. A. Goldman, contains many novelties, some of which are here described. Two of the new species, the largest yet discov-ered, are separated subgenerically under the name Megadontomys. Seven of the others belong to a well marked group distinguished by rather large size, long, soft and very dense fur, dark color, and a general agreement in cranial and dental characters.* It is but a step from P. guatemalensis of this series to totontepecus of the mexicanus series, and another step covers the related tehuantepecus and oaxacensis. Three others (felipensis, gratus, and levipes) be-long to the truei-difficilis group, of which P. hylocetes may be an aberrant member, and one (muscidoides) is distantly connected with the leucopus series. Standing widely apart from all of these is P. mekisturus, an extraordinary long-tailed animal, perhaps arboreal, from the mountain slope at Chalchicomula, Puebla. Subgenus MEGADONTOMYS nobis,. Type, Peromyscus (Megadontomys) thomasi sp. nov., from Mts. near Chil-pancingo, Guerrero, Mexico. Characters. — Size large (the two known species as large as roof rats) ; ears and tail long and very scantily haired ; pelage long, soft, and very dense. *The new species in the series in question are: zahrynchus, guatemalen-sis, Upturns, and the slightly divergent megalops, aurUus, and comptus. 27— Blot.. Soc. Wash, Vol. XII. 1898 (115)
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