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Show 1870.] MYOLOGY OF PLATYDACTYLUS JAPONICUS. 415 columella, covered in by the membrane which connects the upper edge of that bone with the parietal, at the point of attachment of the membrane corresponding to the alisphenoid, and is inserted into the upper border of the pterygoid, behind the columella. The other muscle is internal, and arises from the membranous alisphenoid, beneath the last, in front of the exit of the third division of the fifth nerve, also from a membranous expansion attached to the external apophysis of the basisphenoid, and is inserted into the inner border of the pterygoid bone within and behind the last muscle, extending as far backwards as the inner border of the os quadratum ; but it is not actually attached to this bone. Is it possible that these two muscles represent the tensor and laxator tympani ? Their origins correspond to a certaiu extent; but the insertions are different. It is true that the latter approaches very closely to the os quadratum, which, although not the malleus, is next door to it. They seem to present as much correspondence as can be expected in a skull so widely different from that of mammals. Digastric.-A thin muscle arising from the posterior front of the parietal and squamosal, immediately in front of the exoccipital; it passes downwards over the latter and behind the os quadratum, and developes a slender tendon, which is inserted into the extreme posterior point of the articular piece of the mandible. This appears to correspond to the posterior belly of the digastric. Pectoralis major arises from the whole lengtb of the middle line of the sternum, from about the centre of the interclavicle, as far as the end of the xiphisternum. The posterior fibres also arise from the rectus abdominis by means of a tendinous intersection ; it is inserted into the summit of a hook-like process on the lower and outer surface of the humerus immediately beyond the humero-scapular articulation, which appears to correspond to the greater tuberosity, and into the surface of the bone beyond it. Deltoid arises from the lower anterior and upper surfaces of the inner or lower extremity of the clavicle; it turns back between it and the coracoid, passing in front of the former, and covering the anterior part of the shoulder; it is inserted into the outside of the humerus, immediately beyond the head of the bone and in front of the outside head of the triceps. Supraspinatus arises from the anterior half of the coracoid, and is inserted into the anterior point of the head of the humerus, in front of the insertion of the pectoralis major. This is called epicoraco-humeral by Mr. Mivart; nevertheless I would venture to suggest that it corresponds to the supraspinatus, because it arises from the coracoid, and that process, attached as it is to the anterior part of tbe scapula, would point to the supraspinous fossa. Teres minor arises from the anterior border of the scapula, at its junction with the coracoid, just dorsad of the coraco-scapular fenestra; it is attached to the capsule of the joint, and is inserted into the upperside of the head of the humerus, immediately beyond its articulation ; it is bound down at its insertion by an aponeurosis attached to the long head of the triceps, and is covered over by the deltoid. |
