OCR Text |
Show 1904.] FROM MADAGASCAR AND EGYPT. 169 material is necessary before the precise affinities of this bird can be fully determined, probably from no similar fragment of any other bone of the skeleton could so much information be derived. The outer condyle, the upper angle of which extends some distance vrp the antero-external border of the bone, seems to be larger in proportion to the inner than in the other Ratites except possibly Struthio. The condyles are very distinctly separated by a vex-y well-marked intercondylar groove, in this respect more resembling the tibia? of Casitarius and Rhea, and differing from those of JEpyornis and Struthio, in which the groove is very shallow. The post-conclylar processes are not nearly so prominent as in Struthio, but about as in Dromceus; the outer post-condylar process does not extend nearly so far upwards as the condyle does anteriorly, and is sharply separated from it almost at a right angle (see text-fig. 15, B, a.) which fox-ms tlxe most distal point of tlxe bone. The consequence of this arrangement is that the condylar articular surface looks mox-e forward than is usually the case, though some approximation to this condition is seen in Struthio, and still more in Rhea. The surface between tlxe post-condylar px-ocesses is slightly concave and passes gently into the posterior surface of the shaft, which, like the whole articular end of the bone, is strongly compressed fx-onx before backwards. The lateral faces of the condyles bear deep pits for the attachment of ligaments (text-fig. 15, B). Text fig. 15. Distal end of left tibio-tarsus of JSremopezus eoccenus. A. From front. B. From side. C. From back. a., angle between outer condyle and post-condylar surface; e.g., extensor groove: i.e., inner condyle ; o.c, outer condyle ; t., tubercle marking position of extensor bridge. The figures are | natural size. The posterior face of the shaft passes by a gentle slope into tlxe sharp antero-internal bolder of the bone, which is continuous with the upper angle of the inner condyle, as in Casuctrius and Dromceus. The anterior face of the shaft near its inner border is deeply |