OCR Text |
Show 330 MESSRS. B. C A. WINDLE AND F. G. PARSONS ON [Mar. 7, the outer side of that bone is not present. In Myrmecophaga the humeral head of the biceps, already described, may Avith considerable probability be looked upon as a suppressed and modified brachialis anticus (11, 12, 13). In Tamandua (14, 15) the condition is practically the same. In Cyclothurus (17, 18, 19, 20) the muscle rises below the deltoid ridge. In the Dasypodidce the external part of the muscle is present and rises from the neck of the humerus in the usual mammalian manner. This applies to Dasypus (22, 23), Tatusia (25), and Chlamydophorus (27). In the Manidce the outer or longhead Avas found, as in the last-mentioned family, in every case (29, 30, 31, 32, 33, 34). In only one case was the internal head found (29), and in that it rose from the front of the humerus below the deltoid ridge. In two cases (30, 31) this head AA-as carefully looked for, but without success ; it is, hoAvever, frequently so closely fused AAith the external head that, unless specially sought for, it is very easily overlooked. In Oryeteropus (35, 36) the external head Avas present as usual, but the internal bead was present, as a few fibres rising from below the deltoid ridge, in one specimen only (35). Triceps and Anconeus.-In the Bradypodidce, Bradypus (1, 2, 3, 4, 5) and Cholcepus (8, 10) have the usual three heads, and the inner of these tends to fuse Avith the anconeus. In the Myrmecophagidce the muscle is often very specialized. Pouchet (II.) describes six heads, three superficial and three deep. The three superficial he calls : (a) '* La longue," which is equiA'alent to our longus, though a few of its fibres rise from the dorsum scapulae and remind us of the arrangement found in some of the Mustelidas amongst the Carnivora (Proc. Zool. Soc. 1897, p. 394). This arrangement was also found in the B.C.S. specimen (11). (b) " L'accessoire interne," which Ave haA'e already alluded to as a displaced latissimo-olecranalis. (c) " L'accessoire ex-terne," which rises by tendon between the two parts of the deltoid and becomes fleshy as it descends. It Avas not present in the specimen which Ave examined from the B.C.S. The three deep heads of Pouchet are : (d) " Le vaste interne," (e) " Le vaste externe," and (/) " L'accessoire median." The two former are simply the usual external and internal heads of the muscle, wbile the third consists of some fibres from the short head of the biceps to the triceps, which we did not find in the B.C.S. specimen. Macalister (13) points out that the internal head becomes tendinous and passes through a groove behind the internal condyle, through which it plays as through a pulley, its tendon then becoming continuous AAith one of the heads of the flexor of the digits. This remarkable arrangement, also met with in Oryeteropus, must, as Macalister remarks, give great additional poAA'er to the latter muscle and is a further example of the unusual confluence of usually separate muscles in this Order. In Tamandua (14, 15) the long bead is very large, rising from all that part of the dorsum scapulas beloAv the inferior spine Avhich is not occupied by the teres major. In one case (15) an additional |