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Show 280 MESSKS. B. ('. A. WINDLE AND V. G. PARSONS ON [Nov. 3, Posterior Tibial Region. Gastrocnemius.-The two heads of this muscle rise, as usual, from just above the condyles of the femur; the inner is generally more extensive in its origin than the external and often extends over a considerable portion of the popliteal surface of the femur. One of the most notable points in this muscle in the Ungulata is the absence of fabellae in its origins, The only member of the order in which we have found fabellae is the Hyrax, and in it only the outer one was present. The tendo Achillis shows the characteristic rope-like twisting previously described by one of us (Journ. Anat. vol. xxviii. p. 414) very well, and in some animals, e. g. the Elephant (79) and Musk-Deer (31), the tendons remain separate as far as the calcaneum. In the Chevrotain, Kinberg (X.) describes the outer head as having an anterior and posterior origin. In the Hippopotamus, Gratiolet and Alix (III.) say that the origins are continued down to the tibia. The expansions from the thigh-muscles forming a sheath for the gastrocnemius tendon have already been described. The nerve-supply is always the internal popliteal. Soleus.-In the Hippopotamidae (1, 3) and Suidae (4, 6, 9, 11, 12, 14) this is either wanting or, more probably, has shifted its origin upward to the external condyle of the femur and is fused with the external head of the gastrocnemius. In Cuvier and Laurillard's Peccary (13), however, its origin is drawn rising from the surface of the peroneus quarti digiti. In the Tragulidae (20, 22) the muscle is distinct, and in our specimen (22) rose from the middle third of the fibula. In the Cervidae (29, 30) it rises from the external condyle, but is a distinct, though small, muscle. In the Bovidae (40, 48, 54, 55) it usually rises from the rudimentary head of the fibula and joins the outer head of the gastrocnemius. In the Tapiridae (61, 62) it is condylar and very small. Turner (XVI.) failed to find it at all. In the Equidae (63, 64, 65) it rises from the external tuberosity of the tibia. W e have no record of it in the Rhinocerotidae. In the Procaviidse (74, 75) it comes from the head of the fibula and is fairly well developed. In the Elephantidae (74, 77, 79) it is also well developed, rises from the head of the fibula and is inserted separately into the calcaneum. From the foregoing it will be seen that this muscle in the Ungulata is subject to a good deal of variation, but in all except the Subungulata is feebly developed. In the Hippopotamidae, Suidae, Cervidae, and Tapiridae its origin is usually shifted up to the external condyle, while in the other families it rises either from the fibula or from the adjacent external tuberosity of the tibia. Its nerve-supply is the internal popliteal. Plantar is.-This muscle is always present in the Ungulata. In the Hippopotamus (1) it has a very large muscular belly rising from above the external condyle of the femur; this tendon in the sole has a few fleshy fibres on its deep surface and is the only |