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Show 1895.] ANATOMY OF PIPA AMERICANA. 837 It is triangular in form and arises from the clavicle up to about halfway up, and from the base of the scapula anterior to the attachment of the clavicle. The fibres converge to an insertion upon the humerus nearer to the shoulder-blade than that of the deltoid. In Pipa the smaller head of the deltoid only arises from the clavicle and does not reach the omosternum ; it may therefore rather correspond to the muscle just described in R. guppyi than to the clavicular head of the deltoid of that frog and of Rana esculenta. Pectoralis minor. This muscle, to which I provisionally give the above name, is another muscle which is apparently absent from the shoulder of Rana esculenta, as I can find no description of it in Ecker. But it is present in Rana guppyi. It arises from the coracoid, but from the lower part, not from the upper part where the coraco-humeralis takes origin. It is, indeed, rather related to the subscapularis running parallel with that muscle, and indeed partly covered by it for nearly the whole of its course, but everywhere separable from it. It is a fleshy muscle with fleshy origin and insertion. At the insertion it bifurcates and is attached to the humerus on either side of the tendon of insertion of the posterior sternal portion oF the pectoral. I find this muscle in Pipa, where, however, it is quite insignificant compared with the large muscle of Rana guppyi; it arises from the lower portion of the coracoid, and is hardly distinguishable either at its origin or insertion from the coraco-humeralis, except that it is entirely fleshy, while the coraco-humeralis is inserted by a strong tendon. Muscles of the Leg. When the muscles of the thigh are exposed to view by removing the skin, five muscles are visible on the ventral surface in Rana. R. guppyi is precisely like R. temporaria. These muscles are, commencing with the anterior border of the thigh, vastus internus, sartorius, adductor magnus, rectus internus major, and r. i. minor. In a similar preparation of the corresponding region of Pipa it is necessary, in order fully to display the muscles, to cut away the origin of the rectus abdominis; for this muscle in Pipa arises from nearly the entire length of the femur, and naturally, therefore, entirely hides the vastus internus. W h e n this dissection is effected no less than seven muscles are visible, six of them for nearly the whole of their course, as shown in the accompanying drawing (fig. 4). But a very important muscle of the thigh of Rana is totally wanting in Pipa-that is, the sartorius; I could find no trace of this muscle *, the absence of which is possibly to be accounted for by the physical impossibilities introduced by the attachment to the femur of the abdominal musculature. The adductor magnus is more completely divisible into two parts than it is in Rana. In Rana the muscle is, as it were, split, 1 Mayer calls " sartorius " what I term semitendinosus (anterior head). |