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Show 1S99.] THE MYOLOGY OF THE EDENTATA. 323 or portions of the pectoral mass. Begarding as Ave do this mass and the panniculus of the region as portions of the differentiated lateral sheet of muscle carried out by the limb-bud, Ave believe achselbogen to be a rudimentary condition represented in its fullest development by the presence of a muscular floor to the axilla, and that in both these conditions Ave have to do with a section of the sheet lying betAveen the pectorals and the latissimus dorsi. This arrangement has been noticed in Dasypus (22, 23, 24), Tatusia (25, 26), and Chlamydophorus (27, 28). In the last-named animal Macalister describes a special bundle of fibres rising from the mammillary processes of the first tAvo lumbar vertebras aud gaining insertion into the posterior inferior angle of the scapula. W e can quite concur Avith his statement that this bundle is not found in any other Edentate. Latissimo-olecranalis.-This muscle is always present in Edentates, and is singularly well developed in many of them. In the Bradypodidce the muscle is not of great size; in Bradypus it is inserted into the internal supra-condylar ridge (1, 2, 4, 6), Avhile in Cholcepus it is attached to the arch of the large supra-condvlar foramen. In the Myrmecophagidce the muscle is of fair size and (in the specimen 0.11 at the B. C. S.) attached to the inner side of the olecranon. Pouchet (II.) speaks of an " accessoire interne " arising from the infraspinous fossa in his specimen (12). This may be a displaced latissimo-olecranalis, though the condition is clearly abnormal, since it was neither found by Macalister nor by ourselves (11). Iu Tamandua (14) we found the muscle with its usual attachments ; but Bapp (TIL) found it rising from the scapula close to the teres major, a condition which nearly agrees AAith that described by Pouchet as the " accessoire interne." In Cyclothurus the muscle has a more extended insertion than in the other Ant-eaters ; it is attached to the forearm from the olecranon process to the palmar fascia (17, IS, 19, 20). Humphry (IV.) says that from its insertion the palmaris longus takes origin, this being one of several instances of unusual continuity between muscles generally separate one from another in other Orders. In the Dasypodidce the muscle is very large and often has further origins than that which it obtains from the latissimus dorsi. In Dasypus (22) we found it rising («) from the main insertion of the latissimus dorsi, (b) from the dorsum scapulas, and (c) from that part of the latissimus dorsi muscle which arises from the thoracic vertebras. The muscle covered the dorsal and internal aspects of the arm and was folded round the triceps in such a Avay as to render that muscle invisible until the latissimo-olecranalis was removed. The insertion was into the olecranon and upper half of the subcutaneous margin of the ulna. This is the maximum development of the muscle so far met with by us in any mammal. Galton does not mention any independent origin from the scapula in this animal (23), but otherwise his description agrees Avith our own. Cuvier and Laurillard (24) figure the same extensiA'e insertion. In Tatusia the muscle is very large, and in one specimen (25) obtains an extra |