HAPLODONTID&—VISCERA OF HAPLODON RUIUS. 583 
anterior extremity is somewhat three-pronged ; the inner anterior corner 
forms a broad shelf, upon which the inner half of the astragalus is imposed. 
The astragalus has a well-marked trochlear surface for the tibia, and a large 
forward projection, or plate-like process, upon the convex oval extremity of 
which the lenticular naviculare is articulated by a cupped facet. A large os 
intermedium or centrale is wedged in between the naviculare and the row of 
cuneiform bones. The latter are three in number, side by side, bearing upon 
their proximal faces the centrale, and supporting at their distal ends the 1st, 
2d, and 3d metatarsals. An irregularly nodular cuboid supports the 4th and 
5th metatarsals. On the inner side of the inner cuneiforme, and at the base 
of the 1st metatarsal, may be observed a small flattened and somewhat semi- 
lunar ossicle close-pressed to the side of the foot. 
; There are five metatarsals; the three intermediate ones are of approxi- 
mately equal lengths; the 5th is a little shorter, the 1st shorter still, but not 
so much reduced as the 1st metacarpal. The head of the 2d metatarsal is 
locked in a recess between the two lateral cuneiform bones. 
There are fourteen phalangeal bones, disposed as in the hand; two to the 
hallux, three apiece to the other digits. 
The os hyoides and os penis are described in speaking of the soft parts 
of the organs to which they respectively pertain. 
D.—DESCRIPTION OF THE VISCERA 
Heart.—The heart is an inch long, not peculiar in shape. Both auricles 
are very distinct, standing flap-like away from the ventricles, or only con- 
nected by a constricted pedicellate base, especially the left one. In the state 
observed, they were engorged with blood-clot; the ventricles were empty. 
The right ventricle is much thinner-walled than the left; the aorta arches to 
the left over the pulmonary artery, which at: first is directed to the left, and 
then backward beneath the arch of the aorta, after which it divides to right 
and left, proceeding to the lungs. 
Respiratory organs —There is a well-developed darynx, in which the 
principal parts are completely cartilaginous. The thyroid is the largest of 
these, somewhat semilunar in general outline, but with a median superior 
projection, median inferior emargination, and rather long, slender postero- 
inferior corners, which are firmly attached to the lower border of the 
cricoid at each side of the latter. The cricoid is large, stout, and completely 
