| OCR Text |
Show 836 MR. P. E. BEDDARD ON THE [Dec. 3, pendently of and anterior to1 the insertion of the lateral half of muscle. The posterior half of the muscle is the larger ; it ends in a flat, widish tendon, which is joined behind by the tendon of the latissimus dorsi. Neither part of the muscle has any relation to the deltoid, such as is the case with Rana guppyi; in that frog the tendon becomes adherent to the tendinous sheath of the deltoid before its own insertion. There is a small submentalis. The submaxiilaris (mylohyoid) is divided into two portions, as it is in the Common Frog. The anterior, much the larger, portion runs across the floor of the mouth in the usual way, while the small posterior portion arises from the hyoid. The main part of the muscle arises by six separate digitations from the mandibular margin, as described by Mayer, who gave it on this account the title of " musculus hexagastricus." Pectoro-mandibulce. Beneath the last-mentioned muscle is a sheet of muscular fibres which is totally unrepresented in the Common Frog and which has a very peculiar distribution. The muscle appears to correspond to Mayer's "pectoralis superior," but is not fully described or figured by him. The muscle is inserted along the entire length of the mandibles. It arises from the fascia covering over the sternal region of the pectoral muscles, and completely covers those muscles itself. At one corner it is inserted on to the humerus in common with the pectorals. They may possibly correspond to the cutaneus pectoris of the frog and to the panniculus carnosus of mammals. The sternoradialis is very much larger in proportion in Pipa than it is in Rana. It is at least four times as large as either of the sternal portions of the pectoral, and is indistinctly divisible into three masses. Its tendon, passing to forearm, does not run between the divisions of pectoralis as in Rana. The pectoralis consists of three parts, or, if we include the pectoro-mandibular described above, four separate portions. (1) The abdominal portion is of considerable extent, and the two muscles are separated anteriorly by a fascia continuous with them, which ends anteriorly in a free edge lying on the sternum. Posteriorly the fibres originate from a rhomboidal plate of tendon figured by Mayer, which lies medianly and posteriorly from tendinous intersection with rectus abdominis. (2) The anterior sternal portion is superficial to the sternoradialis; it arises by a thin flat tendon from the middle line of the sternum. (3) The posterior sternal portion is in contact with the sternoradialis for its whole length. The coraco-humeralis is well developed. The deltoid of Rana guppyi does not correspond with Ecker's description of that muscle in Rana esculenta. The scapular and clavicular heads are the same, but there is, in addition, a third head which ought perhaps to be regarded as a distinct muscle. i. e. nearest to the hand. |
