232 
TERTIARY VERTEBRATA OF THE FAYDM. 
The fibnlar facet {fih.) is nearly flat above, but curved a little outwards towards its 
aiitero-inferior border, where it joins the ectal facet for the calcaneuiu is a sharp angle. 
On tin; inner side of the trochlea the body of the bone is slightly concave and i> 
produced backwards and inwards into a considerable prominence. 
The neck is long and is directed more inwards than usual in the true Carnivora ; the 
head bears two facets, a large terminal gently convex surface for the navicular (nav.) and a 
small surface looking outwards and making an obtuse angle with the last; this (cal.) is 
jirobably for contact with the distal end of the calcaneum or perhaps with the cuboid. 
The (dongated ectal facet (ect.) is placed very obliquely to the dorso-plantar axis ; it is 
slightly concave [)Osteriorl 3 - and flat in front. It is sharply bounded on both sides by 
deej) fossse, that in front separating it from the sustentacular facet and having at its 
posterior end the ventral opening of the astragalar canal. The sustentacular facet (.<//.■;. ) 
is oval and gently convex ; it appears to be connected with the distal calcaneal facer 
.above noticed by a narrow band. 
The most notable characters of this astragalus seem to be (1) the great extension 
backwards of the inner half of the tibial surface ; (2) the large size of the astragalar 
foramen ; (3) the presence of a considerable prominence of the postero-internal angle 
of the bone. The dimensions (in centimetres) of this bone are: — 
Greatest length 4'4 
„ width 3‘7 
Width of tibial surface 2‘4 
K. 9269. Plaster cast of the above specimen. ' Made in the Bntish Museum. 
M. 8441. Left astragalus, imperfect proximally. 
51. 8512. Imperfect left calcaneum. The tuber is almost entirely wanting. The ectal facet is oblicpic^ 
and elongated ; it is convex posteriorly and flat in front, its outer border being continuous 
with the small convex fibular facet. The sustentaculum is not very prominent : it 
bears an oval concave facet. The cuboid facet is oblique to the long axis of the bom^ 
and looks inwards and forwards ; it is very slightly concave. The whole bone seems 
to have been short and stout. Presented hy IP. K. de Winton, Esq., llMhl, 
II. 8441a. Imperfect right calcaneum. 
Genus SINOPA, Leidy. 
[Proc. Acad. Nat. Sci. Philad. 1871, p. IIG.] 
1 872. Stypolophus, Cope, Proc. Amer. Phil. Soc. vol. xii. j). TOG. 
1872. Linmocyon (part.). Marsh, Amer. Journ. Sci. [3] vol. iv. {>. 12G. 
1874. Protolomus, Go])Q, Report on Vertebrate Fossils obtained by the Wheeler Expedition in New 
Mexico, p. 13. 
TTiis genus includes small or medium-sized Cieodonts, in the mandible of which the 
first molar is the smallest of the series. 'The lower molars consist of a high anterior 
