In. Lines. Total length 1 4 Width 0 10 Length of nasal bones 0 7 of incisive foramina 0 4¾ Distance between the outer surface of the incisors and the front molar upper jaw 0 5 Longitudinal extent of the three molars of the upper jaw 0 3¾ Length of a ramus of the lower jaw, without the incisor 0 9¾ The molar teeth of the upper jaw are figured in Plate 33, fig. 2, _c._ and 2, _e_; of the lower jaw, fig. 2, _d_. Fig. 2, _b_, represents the incisors of the upper jaw magnified. Fig. 21, _a_, Plate 34, represents the skull, viewed from beneath, fig. 21, _b_, is the side view of the same, and fig. 21, _c_, is the lower jaw. “Specimens were procured at Port Desire, St. Julian, and Santa Cruz; at this latter place they were caught in numbers, (in traps baited with cheese,) both near the coast and on the interior plains. A specimen from Santa Cruz weighed 1336 grains. In the early part of January, there were young individuals at Port St. Julian.”—D. 2. REITHRODON TYPICUS. Reithrodon typicus, _Waterh._, Proceedings of the Zoological Society of London for February 1837, p. 30. _R. vellere suprà pilis flavescenti-fuscis et nigrescentibus intermixtis composito; regione circa oculos, genis, lateribusque corporis auratis, pilis pallidè fuscis intermixtis; partibus inferioribus auratis; rhinario ad latera flavescenti-albo; auribus magnis, intùs pilis flavis, extùs flavis et fuscis, indutis; caudâ suprà pallidè fuscâ, subtùs sordidè albâ; pedibus albis._ DESCRIPTION.—Ears large; tarsi moderate; fur moderately long; general tint of the upper parts brown—of the upper surface of the head blackish; on the cheeks and flanks a rich yellow tint prevails; the under parts of the head and body are bright yellow; the feet are white; the tail is brownish above and dirty white beneath. The ears are tolerably well clothed with hairs, and these are of a yellowish colour, excepting on the fore part, externally, where they are brown; the tarsi are covered beneath with grayish brown hairs; the hairs of the moustaches are numerous and moderately long, black at the base and grayish at the apex. The hairs of the back are deep gray at the base, broadly annulated with yellow near the apex, and black at the apex; on the upper surface of the head the hairs are very narrowly annulated with yellow, hence a blackish hue prevails. The longer hairs on the back are black; the hairs of the throat and belly are gray at the base, and broadly tipped with yellow. The incisors are yellow.