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, i, ia; LIV, Figs. 5, 6, u ; LIX, Figs. 1-5 ; LX). 



Protopromverra Amegh.; Nuevos Restos Mamif. F6s. Patagonia Austral, 

 pp. 26-27, Aug., 1891 ; Revista Argentina Hist. Nat, I, entr. 50, pp. 

 312-313, 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. i-ib, 3*2, 4; LX, figs, i, ia, 2-30). Dental 

 formula f, 1, f, t. 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. 

 minuta (PI. LX, figs, i, 3). The anterior molars are of the characteristic 

 thylacyne type, while the fourth resembles the last upper molar of Dasytirns. 

 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 



