TI-:HTIAUr YEliTEiniATA OE THE IAVTCM. 
OG 
Those two lacots a, re so])aratc(l froin one another })osteiiorly by a narrow groove, 
and anteriorly l)y a dee]) Ibssa. There; is also a deep fossa lying to the inner 
side of the ante'rior part of the sustentacular (acet. Anteriorly this siirface joins 
that for the cul)oid {cuh.), making an angle of about 100° with it. 
'flu; cuboid surface {cub.) is about one-third of the whole distal articulation. 
It is gently convex in all directions, and is sejearated from the navicular surface 
by a slight obliepie ridge. The navicular surface [nao.) occupies nearly all the 
rest of the distal face of tlie bone; it is strongly convex from side to side, and 
slightly so from before backwards. Internally it is continuous with a small facet (U.)’ 
Avhich may indicate the existemee of a distinct tibiale such as occurs in some 
Amblypoda. On the anterior face of the bone the lower edge of the tibial surfice 
is separated from the upper edge of the cuboid-navicular surface by an interval of 
about 2 to d cm., in which tlie surlace is concave from above downwards. 
This astragalus, though superticially similar to that of Elephas, differs from it 
fundamentally. Among the peunts of difference are : — (1) articulation with cuboid 
and conscapient did'erent form of the distal surface ; (2) much larger surface for 
fibula ; (d) presence of a large and somewhat concave surface for the internal 
malleolus (in the early Proboscidea this seems to have been present, see below) ; 
(4) wide difference in the form and projjortions of the two calcaneal facets; in 
Eleplias the ectal facet, in Arsinoitherium the sustentacular, is much the larger. 
The likeness to the astragalus of the Amblypoda is somewhat greater, particularly 
in the presence of both cuboid and navicular facets. But the form of the calcaneal 
facets is different, and the posterior notch is slightly marked, while in the Amblypoda 
it may even be converted into a foramen. 
The calcaneum (text-fig. d2, 1 a, 1 b) is a very short stout bone somewhat like 
tliat of the Dinoccrata. The tuber calcis (t.c.) is very short and thick, and terminates 
posteriorly in a great rugose mass of bone. The ventral surface is greatly swollen at 
the sides, but in the middle line there is a deep concavity. There are two oval, 
obliquely-arranged facets for articulation with the astragalus. Of these the ectal (ec.) 
is concave from before backwards, while the inner (sustentacular) facet (sii.s.), which 
is much the larger, is flat in front and convex behind, owing to tlu' deflection of its 
hinder portion. The two surfaces are separated posteriorly by a deep narrow cleft 
which, towards the front, becomes wider and dee[)er. The anterior edge of the sus- 
tentacular surface forms the up))er border of a small facet lying at right angles to 
it (Inav.), and probably indicating that tlu're was a small articulation with tlie 
navicular. 'I'he cuboid facet (cub.) is small and oval, its upper inner angle being 
continuous with the small navicular facet just desci-ibed. Beneath the navicular 
and cuboid articulations is a valley bounded below by a rugose and swollen border. 
'I'lie fibular facet (Jib.) is large ; it looks outwards and upwards, and is convex 
from before backwards, while its ujiper border meets the ectal facet in a sharp 
