394 
PATAGONIAN EXPEDITIONS ! PALAEONTOLOGY. 
Pelvis, pubic symphysis, approximate length ...... .0495 
Astragalus, length . . . . . . . . . . . .016 
“ greatest width of trochlea ....... .009 
“ length of trochlea . , . . . . . . . .010 
“ width of neck ......... -0055 
“ “ “ head ......... .0065 
AMPHIPROVIVERRA Ameghino. 
(Plates LIII, Figs. 1, 1 a; LIV, Figs. 5, 6, 11 ; LIX, Figs. 1-5 ; LX). 
Protofiroviverra Amegh.; Nuevos Restos Mamif. Fos. Patagonia Austral, 
pp. 26-27, Aug., 1891 ; Revista Argentina Hist. Nat., I, entr. 5 a, pp. 
3 1 2-3 1 3, Oct., 1891. Preoccupied by Protoproviverra Lemoine. 
Amphiproviverra Amegh. Revista Argentina, etc., I, footnote p. 397, 
1891. 
Small, highly carnivorous marsupials, in which the protocone on the 
last upper molar is basin-shaped and the heels of the lower molars are 
broad and strongly bicuspidate. 
Dentition (Pis. LIX, figs. 1-1 d, 3 a, 4; LX, figs. 1, 1 a, 2-3 a). — Dental 
formula i, -f, f, i- The median upper incisors are styliform, and approxi- 
mated at the tips, as in the opossums and dasyures. The crowns of the 
lateral teeth are spatulate in shape. The incisor series is placed obliquely, 
so that the procumbent median pair are the most anterior. Its members 
increase regularly in size from the first to the fourth. The canines are 
long and slender, projecting below the lower border of the mandible when 
the jaws are closed (PI. LX, fig. 3). The anterior and median premolars 
are simple-crowned, double-fanged, piercing teeth, much compressed 
laterally. The median premolar supports a small heel cusp. The pos- 
terior premolar is enlarged, its crown projecting below the level of the 
molars. It is recurved to about the same degree as the tooth preceding 
it and also carries a small heel cusp. The anterior premolar is separated 
from the canine and median premolar by diastemata. The latter tooth is 
almost in contact with the posterior premolar in A. manzaniana and A . 
7 ninuta (PL LX, figs. 1, 3). The anterior molars are of the characteristic 
thylacyne type, while the fourth resembles the last upper molar of Dasyurus. 
The first, second and third increase regularly in width, although retaining 
about the same antero-posterior diameter. In these teeth, the protocone 
is large, inclosing a basin-shaped depression, on both margins of which 
