DESCRIPTION.—Fur very soft and silky, and extremely long—the ordinary fur of the back measuring nearly three quarters of an inch, and the longer hairs one inch in length; ears moderate; tail nearly as long as the body; muzzle much pointed; general colour gray, washed with yellow, the under parts pale gray, or grayish white; feet brown; ears and tail well clothed; the hairs on the inner side of the ears are chiefly of a yellow colour, those on the upper surface of the tail are brown-black, those on the under part are dirty white; the hairs of the back are deep gray at the base, broadly annulated with yellow near the apex, and dusky at the apex; the longer hairs are grayish black; the hairs of the moustaches are dusky at the base, and whitish beyond that part; the claws are long, and but slightly curved; the incisors are slender; those on the upper jaw are yellow, and those of the under yellow-white. In. Lines. Length from nose to root of tail 5 4 of tail 3 4 from nose to ear 1 2 of tarsus (claws included) 1 0½ of ear 0 6½ Habitat, Coquimbo, Chile, (_May_.) This mouse is remarkable for the great length and softness of its fur, even among the species here described, most of which have very loose, long and soft fur. The molars of the upper jaw are figured in Plate 33, fig. 6, _b._—molars of the lower jaw, fig. 6, _a_. “Inhabits dry stony places, which character of country is general in this part of Chile.”—D. 19. MUS NASUTUS. PLATE XVII.—Fig. 2. Mus nasutus, _Waterh._, Proceedings of the Zoological Society of London for February 1837, p. 16. _M. suprà obscurè flavescenti-fuscus, ad latera fulvescens; subtùs obscurè fulvo tinctus: pedibus pilis obscurè fuscis tectis; unguibus longis; auribus mediocribus; caudâ corpore breviore, suprà fuscá, subtùs sordidè albâ: rhinario producto._