TERTIARY VERTEBRATA OF THE EATtM. 
The libiihir facet {fih.') is nearly flat above, but curved a little outwards towards its 
antero-inrerior border, where it joins the ectal facet for the calcaneum is a sharp angle. 
On the inner side of the trochlea the body of the bone is slightly concave and is. 
produced backwards and inwards into a considerable prominence. 
The neck is long and is directed more inwards than usual in the true Carnivora ; tlie 
liead 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 
])robaI)ly for contact with the distal end of the calcaneum or perha])S with the cuboid, 
d’he (dongated octal facet (cct.) is placed very obliquely to the dorso-plantar axis; it is 
slighily concave [)Osteriorl\' and flat in front. It is sharply bounded on both sides by 
d(‘ep fossm, 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 (.va.v. ) 
is oval and gently convex ; it appears to be connected with the distal calcaneal facet 
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 
M. 9259. Plaster cast of the above specimen. Made in the British Museum. 
M. 8441. Left astragalus, imperfect proximally. 
Mi. 8512. I mperfect left calcaneum. The tuber is almost entirely wanting. The ectal facet is oblique 
:uid elongated ; it is convex ])osteriorly and flat in front, its outer border being continuous 
with the small convex fibular facet. The sustentaculum is not very {)rominent ; it 
bears an oval concave facet. The cuboid facet is oblique to the long :ixis of the bonc! 
and looks inwards and forwards ; it is very slightly concave. Tlie whole bone seems 
to have been short and stout. Presented hy W. E. de Winfon, Esq.., li.H>3. 
M. 8441a. Imperfect right calcaneum. 
Genus SINOPA, Leidy. 
[Proc. Acad. Nat. Sci. Philad. 1871, p. 116.] 
I 872. Slypolophus, Cope, Proc. Amer. Phil. Soc. vol. xii. {). 466. 
1872. T/hnnacyon (part.). Marsh, Amer. Journ. vSei. [3] vol. iv. p. 126. 
1874. J*ri>tofomus,(do\)<i, Report on Vertebrate Fossils obtained by the Wheeler Expedition in New 
l\l(‘xico, p. 13. 
'I’liis genus includes small or medium-sized Creodouts, in the mandible of which the 
first molar is the smallest of the series. T'he lower molars consist of a high anterior 
