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PATAGONIAN EXPEDITIONS : PALAEONTOLOGY. 
exactly the same size, forming digits of nearly equal length. Of the 
median digit (III) the proximal phalanx is slightly shorter than in the 
other digits, but broader, more depressed and symmetrical ; the second 
and ungual phalanges are both longer and broader than in the lateral 
digits, but also more depressed and flattened. 
The pelvis (Pis. XXVI, fig. i ; XXVII, fig. 17) displays a number of 
differences from that of Nesodon. The ilium has a somewhat longer neck, 
which is thin and laterally compressed and has no distinct ilio-pectineal 
process or pubic border, having lost, as in the other genus also, the 
original trihedral shape. The iliac expansion or plate is relatively nar- 
row and but little everted and the gluteal surface is nearly flat ; the crista 
shows a slight tendency to a division into dorsal and ventral portions, 
which, however, are much less distinct than in the Litopterna. The 
acetabulum is of a slightly depressed, oval shape and the sulcus for the 
round ligament is relatively much larger than in Nesodon. The ischium 
is slender and compressed and has no definite tuberosity or sciatic notch ; 
the pubis also is slender and enters into a long symphysis with its fellow. 
The obturator foramen differs in shape from that of Nesodon in being 
broader and less regularly oval. 
The femur (PI. XXVII, figs. 1-3) besides being smaller and lighter 
than that of Nesodon , differs from it in a number of details. The head 
is set upon a more distinct neck and is lower, not rising above the level 
of the great trochanter ; the pit for the round ligament is even smaller, 
though a trifle deeper, than in the last named genus and the notch 
between head and great trochanter is deeper and narrower. The pos- 
terior face of the proximal part of the shaft is very flat and smooth and 
there is no intertrochanteric ridge. The second trochanter is more prom- 
inent than in Nesodon , but not so elongate proximo-distally, while the 
third trochanter is distinctly shorter and less prominent than in the latter. 
The shaft has a shape similar to that of Nesodon , but is more compressed 
antero-posteriorly and has a less convex anterior face, and the pit for the 
plantaris muscle is very inconspicuous. The rotular groove and femoral 
condyles do not differ in any significant features from those of Nesodon. 
The patella (PI. XXVII, fig. 16) is very similar to that of the latter, 
but is relatively more elongate proximo-distally, which is chiefly due to 
the greater extension of the external part of the distal border, and it has 
the same great antero-posterior thickness ; the articular surface for the 
