rjAFLODONTIDJE— VISCERA OF HAPLODON ltUFUS. 583 



anterior extremity is somewhat three-pronged; the inner anterior corner 

 forms a broad shelf, upon which the inner halt' 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 navicularc 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 arc three in number, side by side, hearing 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 larynx, 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 



