428 
PATAGONIAN EXPEDITIONS I PALEONTOLOGY. 
have been broken, but enough of the left squamosal bar remains to show 
that the malar extended to the glenoid fossa. The squamosal portion of 
the arch is not inflated, as it is in Petaurus , Trichosurus and others of 
the higher phalangers. 
The palate is deeply concave both antero-posteriorly and transversely. 
The incisive foramina extend beyond the premaxillary suture to a point 
opposite the anterior premolars. Two antero-posteriorly elongated pala- 
tal vacuities are present, extending from a point opposite the anterior 
extremity of M- to M-. Neuro-vascular canals perforating the posterior 
margin of the palate are present, as in the majority of marsupials. The 
palato-narial border is greatly thickened and elevated in a manner resem- 
bling Didelphys. 
The infra-orbital foramen is large, opening above the anterior root of 
the upper sectorial. 
Mandible (PL LXIII, figs. 4 -6a \ text fig. 8). — The mandible is long, 
slender and shallow in the smaller species, deep and probably less elon- 
gated in the larger forms. The rami are unfused. The symphysial im- 
pression extends as far back as the anterior half of the sectorial. The 
coronoid and angle are not preserved in any of the specimens studied. 
Two mental foramina are usually present, one beneath the sectorial, the 
other beneath or slightly anterior to the last vestigial tooth. Occasionally 
there are two posterior foramina somewhat variable in position. 
Paleothentes arate (Moreno) Ameghino. 
(Plate LXIII, Figs. 2, 2 a ; Text Fig. 8 .) 
Palceotenthes aratce Moreno ; Patagonia, Resto de un Continente hoy 
submergido, p. 22, 1882 ( nomen nudum). 
Palceothentes aratce (Moreno) Amegh. ; Enum. Sist. Especies Mamif. Fos. 
Patagonia Austral, p. 5, 1887. 
Epanorthus aratce (Moreno) Amegh. ; Contrib. al Conocimiento Mamif. 
Fos. Rep. Argent., pp. 272-273, PI. I, Figs. 10-12$, 1889. 
Epanorthus aratce (Moreno) Trouessart; Catalogus Mammalium, p. 1202. 
Represented in the American Museum collection by a fragment of the 
right maxilla (No. 9549 American Museum) from Santa Cruz, retaining 
the median and posterior premolars and the second, third and fourth 
