OCR Text |
Show 1006 MESSRS. B. C A. WINDLE AND F. G. PARSONS ON [Dec. 19, slips are given off to all five toes. The tendon is joined in the sole by a slip from the tibialis posticus accessorius. Popliteus.-In the Bradypodidce (1, 2, 4, 8, 9, 10), Myrmecophagidce (12, 14, 17, 19, 20), and Manidce (29, 32, 33, 34) this muscle is large, occupying the upper half of the tibia; its origin is from the outer condyle, and a sesamoid cartilage or bone is developed in its tendon. In the Orycteropodidce (35, 36) its insertion is singularly extensive, but no sesamoid is mentioned as having been observed. In Dasypus (22, 23) two tendons of origin were noticed, the anterior and larger coming from the outer side of the condyle and the external semilunar cartdage, the posterior and smaller from the posterior part of the condyle. In Tatusia (25) and Chlamydophorus (27, 28, 28a) this double origin was not seen. In no member of the Dasypodidce was a sesamoid cartilage observed. The Edentata are. characterized, as an order, by the large size of their popliteus. Tibialis posticus.-In the Bradypodidce this muscle is single and small; it usually rises from the middle or lower part of the shaft of the tibia, and is inserted into the entocuneiform bone. In the other families (Myrmecophagidce, Dasypodidce, Manidce, and Orycteropodidce) the muscle is usually double, the more external being inserted into the navicular or sometimes the entocuneiform, whilst the other is often larger and passes to the tibial ossicle on the iuner side of the foot. This additional tibialis posticus is called by Galton tibialis posticus secundus, and by Hyrtl tibialis posticus accessorius. Accessorius.-In the Bradypodidce this muscle is always well developed. Humphry states that in Cholcepus (9) and Bradypus (2) it was continuous with the tendon of the soleus. W e have carefully dissected both these animals, but found no connection whatever between the two muscles, nor have other observers described it. In the Myrmecophagidce (11, 14, 15, 17, 20) and Manidce (29, 32, 33) it rises as usual from the lower surface of the calcaneum, and is inserted into the conjoined deep flexors in the sole. In Myrmecophaga (11) it is especially large. In (12) it gives off a special slip to the hallux tendon. In the Dasypodidce (22, 23, 25, 27) there is no muscular accessorius, but its place is taken by the fibrous band which binds the great sesamoid bone of the sole of the foot to the under surface of the calcaneum. In the Orgcteropodidce (35, 36) the muscle is also replaced by tendinous bands from the calcaneum to the outer side of the long flexor tendons. Lumbricales.-In the Bradypodidce we found no lumbricales in our specimens of Bradypus (1) and Cholcepus (8), and their presence is not mentioned by other observers. In Tamandua (14) and Cgclothurus (17), among the Myrmecophagidce, they were not seen but Galton in another specimen of Cyclothurus found three. In Myrmecophaga (12) there were four. The Dasypodidce (22, 25, 27) always have at least four lumbricales, and in one specimen of Dasypus (23) Galton describes seven. In the Manidce (29, 32, 34) |