part 4 .] Lyrlekker: Osteology of Merycopotamns dissimilis. 
151 
Dimensions. —The dimensions are compared below with those of the axis vertebra of 
the Pig ; Merycopotamus in the first, and Sus in the second column :— 
in. In. 
Length of centrum ... ... ... ... ... ... • 2*8 17 
Width of posterior surface of centrum ... ... ... ... ... 1'2 1*2 
Depth of ditto .. ... ... •• ••• ••• ••• ^*9 O' 8- 
Width across anterior articular facets ... ... ... ... ... 22 2"2 
Width of transverse process ... ... ... ... ••• ••• 075 0'3 
Length of odontoid process ... ... ... ... ••• ... 6 6 0‘6 
Width of ditto ... ... ... ••• ••• ••• ••• 
Hinder limb. —Of the hind limb, more or less complete portions of the following bones 
are known, either from the specimens in the British Museum (from which Falconer’s figures 
are taken) or from specimens in the Indian Museum, viz., Innominate, Femur, Tibia, Cal- 
caneum, Astragalus, and Metatarsus. 
Innominate. —The innominate is known from the specimens of the acetabulum figured 
by Falconer (“ F. A. S.,” pi. 68 , Jigs. 1 a/ul 2); the acetabulum is completely circular and 
moderately deep, with a distinct pit for the attachment of the ligamuntum teres; its 
diameter is l'5o inches. 
Femur. —At the proximal extremity the great trochanter is placed higher than in Sus 
and Hippopotamus ; it is also more recurved, and the head is placed more nearly perpendi¬ 
cularly to the neck ; it does not show any distinct impression for the ligainentum teres ; the 
digital fossa is also deeper than in the allival genera. The distal extremity of the femur 
(see Falconer’s figures ) is very different from that of the Pig or Hippopotamus, and is 
unlike that of any living Ungulate; the trochlear surface for the pattella is unusually elon¬ 
gated, and its borders are placed almost parallel to the long axis of the bone, instead of very 
obliquely, as in other Ungulates: the condyles are consequently nearly equal-sized and sym¬ 
metrical. 
Tibia. —The proximal extremity alone of the tibia has been discovered : the articular 
surfaces are nearly equal sized and symmetrical: the prominence for the crucial ligaments is 
bifid ; there is a notch and prominence on the anterior border as in Sus in Hippopotamus 
this border is roughened, but not notched. On the posterior border in Merycopotamns there 
is a narrow notch, which is not found in the other genera- 
Astragalus. —Several views of the astragalus are given in plate 68 of the Fauna 
Antigua. Sivalensis, and we have several specimens of the bone in the Indian Museum, chiefly 
collected in Sind by Mr. Fedden; the specimen that I have measured is from the left side. 
The astragalus of Merycopotamns is formed on the same general plan stu the corresponding 
hone of Hippopotamus and Sus, having distinct sub-equal facets for the articulation of the 
cuboid and navicular bones separated by an intervening ridge, which indicates the non-union 
of the two latter bones. Comparing the astragalus of Merycopotamns, firstly with that of 
Hippopotamus, we find that the former is distinguished by its greater length in proportion 
to its breadth, so that the breadth of' the distal extremity is only equal to one-half the 
length of the bone, whereas in Hippopotamus, the corresponding breadth is equal to rather 
more than two-thirds of the length of the bone. In both bones the calcaneal half of the 
tibial trochlea is considerably the highest and stoutest of the two ; the trochlear surface for 
the calcanemn is almost square in Hippopotamus, while it is oblong in Merycopotamus, and 
there is a deeper pit between this surface, and the commencement of (he tibial trochlea. The 
articular surface for the cuboid in both is placed on a lower level than that for the navicular, 
while the latter extends further up on the posterior surface of the bone : both articular 
surfaces are of approximately equal width, and the ridge between the two is placed obliquely 
to the long axis of the bone. The lateral surfaces of the two bones have the same general 
