220 LLOYD'S NATURAL HISTORY. 
tution of such an utterly meaningless name as Diude/phys 
americana. Still, it must be confessed that if we once break 
through the rule of adopting the earliest specific name pro- 
posed for an animal as its proper designation, it becomes very 
difficult to know where to stop. 
XXII. LESSER THREE-STRIPED OPOSSUM. DIDELPHYS 
IHERINGI. 
Didelphys (Peramys) theringi, Thomas, Ann. Mag. Nat. Hist., 
ser. 6, vol, i., p. 159, and Cat. Marsup. Brit. Mus., p. 364 
(1888). 
Characters.—Although this tiny little species appears at first 
sight to be nothing more than a dwarf race of the preceding, it 
may, according to its describer, be distinguished not only by 
its inferior size, but likewise by the different conformation of 
the skull, and more especially by the marked flattening of the 
region of the forehead. Length of head and body of male 
about 3 inches; of tail 134 inch. 
Distribution———South Brazil. 
XXIII. SINGLE-STRIPED OPOSSUM. DIDELPHYS UNISTRIATA. 
Dideiphys unisiriata, Wagner, Archiv. fiir Nat., vol. viil., p. 360 
(1842); Thomas, Cat. Marsup. Brit. Mus., p. 365 (1888). 
Characters.—Apparently only known by a single specimen, 
this litttle short-tailed Opossum is sufficiently distinguished by 
the single dark reddish-brown line running down the middle of 
the back from behind the shoulders to the rump ; the general 
colour of the upper surface being pale grizzled grey, and the 
hairs tipped with rufous, while the flanks and under-parts are 
bright orange, as are the greater portion of the limbs. The 
ears are very short, rim-like, and nearly naked; and the tail 
has its basal half-inch furred, and gradually passing into the - 
