A PTEliODON MACIiOQNATIIUS. 
231 
M. 8504. Distal end of right luiiuerns. Figured on PI. XIX. figs. 7,7 a. Closely similar to 
C. 0445. 
M. 8440. Distal ends of two similar linmeri. 
C. 8845. Right til)ia, wanting the epiphyses (text-fig. 75). The bone, as a whole, is strongly 
curved, the convexity being anterior. The cnemial crest (ca.) slopes away and 
probably its upper end was overlapped by the patella. It extends about halfway down 
the bone, and terminates in a rugose prominence for the attachment of a ])owerful 
muscle. The upper half of the shaft is trihedral. On the inner face just below the ujijxu- 
end there is a long roughened depression for muscle-attachment (m.). The postei'ior 
face at the uppei- end of the bone is concave from side to side. Towards the distal end 
the shaft widens out a little, but in this specimen the articular region is wanting. On 
the whole, this bone seems to lend some support to the idea that this Creodont may have 
Text-fig. 7<!. 
flight astragalus of (?) Apterodon macrogmithus : A, from above ; B, from below. 
<•«?., facet for calcaneum ; cci., ectal facet : astragalar perforation ; fib., surface for fibula ; nav., facet for 
navicular ; sus., sustentacular facet ; til., surface for tibia. Nat. size. 
been more or less aquatic in its habits. The well-marked rugose surface for th(» 
attachment of muscles at the inner side of the jiroximal end of the shaft (/a.) seems to 
occur also in some Seals and in Lvtra, while that marked m in the figure may 
correspond with a somewhat .similarly situated rugosity in some Seals. The dimensions 
(in centimetres) of this bone are : — 
Length 1.54 
AVndth of proximal articulation 3-7 
Antero-posterior width of shaft at muscular promiueuce . . 
M. 9258. Plaster cast of the above specimen. Made in the British Museum. 
C. 8116. Right astragalus (text-fig. 7(1). The trochlear surface (tih.) is very slightly grooved ; on its 
inner side it is produced backwards in a sort of tongue to the extreme hinder border. 
At the angle between the outer edge of this backward extension and the posterior border 
of the outer half of the trochlea is the large upper opening (/.) of the astragalar canal. 
