OCR Text |
Show 320 MESSRS. B. C. A. WINDLE AND F. G. PARSONS ON [Mar. 7, present, and the latter arises from the inner | or 5 of the clavicle. Omo-trachelian.-This muscle is not a constant feature in Edentate myology. When present, it arises, as is usually the case amongst mammals, from the transverse process of the atlas, and is inserted into the acromion process. In the Bradypodidce it was present in Bradypus (1, 3), being inserted in the latter specimen into the upper angle of the scapula. In another specimen (5) its existence is not mentioned, nor has it been noticed in Cholcepus. In the Myrmecophagidce the muscle was absent in Myrmecophaga (13), but present and well marked in Tamandua (16) and Cyclothurus (18, 19). In the Dasypodidce the muscle Avas absent in two specimens of Dasypus (22, 24) and no mention is made of its presence in a third (23); Macalister, however, records its existence in a specimen. In the Munidce the muscle is well marked, but shifts its anterior attachment from the atlas to the mastoid region of the skull (29, 30, 31, 32). Scaleni.-In no Edentate have Ave seen or met with any record of a scalene muscle lying on the ventral aspect of the subclavian vessels, so that it may be fairly definitely laid doAvn that the scalenus ventralis is a muscle totally wanting in this order. The scalenus longus is attached to a very small number of ribs, another characteristic feature of Edentate myology. The folloAving table gives a list of the attachments of longus and brevis in several specimens:- Longus. Brevis. £radi/2nis(l) 6, 7, 8, 9 C. V. & rib i. 6, 7, 8, 9 C. V. & rib i. (4) Choloepus (10) 2, 3, 4, 5, 6 C. V. &'ribs i, ii. Tamandua (14) 3, 4, 5, 6 C. V. & rib i. 4, 5, 6, 7 C. V. & rib i. Cyclothurus (17, 21) ... 4, 5, 6, 7 C. V. & rib i. Dasypus (22) ribs iii., iv., v. ribs ii., iii., iv. Tatusia (25) ribs i., ii., iii. ribs i., ii. Chlamydophorus (27)... 2, 3, 4, 5, 6 C. V. & rib ii. 2,3,4,5,6 C. V. & rib i. » (-8)... „ „ ,, n Manis (29) 2,3,4, C. V. & ribs ii., iii., iv. 4,5, C.V. & rib i. Rectus thoracis lateralis.-This muscle is, so far as Ave know, characteristic of the Edentates, as Ave have neither met Avith it nor any description of it among other mammals, in the [course of our researches. It continues the direction of the scalenus longus caudalwards, being attached anteriorly to the first rib or pair of ribs and posteriorly to some of the hinder ribs. As a rule, the muscle is external to the rectus ventralis, but AAiien the tAvo overlap, as they did in our specimen of Dasypus (22), the rectus ventralis is the more superficial of the two, a fact Avhich shows that the rectus thoracis lateralis cannot be regarded as a displaced supra-costalis. Indeed, the fact that it is found in Cholcepms (10) co-existing Avith the supra-costalis is alone sufficient to prove this. Macalister considers that this muscle is a lateral displace- |