In. Lines. Length of the skull 2 4 Width 1 3 Length of nasal bones 0 9½ —— of palate 1 2¾ Width of palate between the posterior molars 0 5 Distance between forepart of front incisors and forepart of canine 2 0¾ Distance between forepart of canine and hinder part of last molar 1 0 Length of _ramus_ of lower jaw (incisors not included) 1 10½ “This specimen was caught at Maldonado: it weighed 14½ oz.”—D. 3. DIDELPHIS ELEGANS. PLATE XXXI. _D. vellere longo et molli, corpore suprà cinereo-fuscescente lavalo; pedibus corporeque subtùs albis, oculis nigra circumdatis, interspatio cinerescente; auribus magnis fuscescentibus; caudá, capite et corpore, paulo breviore._ DESCRIPTION.—Muzzle slender and pointed; ears large; tail rather shorter than the head and body taken together; fur long and very soft: general tint of the upper parts of the head and body ashy gray washed with brown; on the sides of the body, especially near the shoulders, a faint yellowish tint is observable; the lower part of the cheeks, the throat, under parts of the body and the feet, are white, with an indistinct yellowish tint; the eyes are encircled with brownish black, which tint is extended forwards on to the sides of the muzzle; the upper surface of the muzzle and the inter-orbital space is pale. The tail is furnished throughout with minute decumbent hairs, excepting a small naked space at the tip beneath, of about one line in length; on the upper surface they are brown, and on the under, they are whitish. The fur of the upper and under parts of the body is deep gray at the base; on the lower part of the cheeks, chin, and on the mesial line of the throat and chest, the hairs are uniform—not gray at the base. The ears are brown, and to the naked eye, appear naked. In. Lines. length from nose to root of tail 4 6 of tail 4 4 of tarsus (claws included) 0 7½ from nose to ear 1 1½ of ear 0 7¼ width of ear 0 7½ Habitat, Valparaiso, Chile, (_October_.)