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Show 322 MESSRS. B. C. A. AVINDLE AND F. G. PARSONS ON [Mar. 7, these muscles amongst the Edentates by saying that the splenius colli is usually absent throughout the Order with the exception of Bradypus, in which animal the splenius capitis is feeble or wanting. Trapezius.-In Bradypus (1, 2, 3, 5, 6) this muscle fails to reach the occiput, a fact which seems to be correlated with the lengthening of the neck due to the two extra cervical vertebras. The origin is from the ligamentum nuchas and the anterior 4th, 5th, and 6th spines. The anterior cervical fibres are continuous with the clavicular deltoid to form a cephalo-humeralis ; the posterior cervical and thoracic fibres are separated from the former by a fibrous interval and are inserted into the spine of the scapula and acromion process. In Cholcepus the anterior part rises from the occiput aud ligamentum nuchas, and is inserted into the lower border of the scapular spine. The posterior fibres can with difficulty be separated from these and are inserted into the whole length of the spine. In the Myrmecophagidce the trapezius forms a continuous sheet. In Myrmecophaga (13), Tamandua (14, 16), and two specimens of Cyclothurus (17, 21) there Avas no occipital origin, but in other specimens of the last-named animal (18, 19, 20) the muscle rose from the occipital curved line. In Cyclothurus the anterior fibres are inserted into the outer part of the clavicle, which is Avell developed in this animal. In Myrmecophaga (11) and Tamandua (14, 16) the anterior fibres form with the clavicular deltoid a well-developed cephalo-humeral, and as usual there is a fibrous intersection in the position of the clavicle. Amongst the Dasypodidce, Dasypus (22) has the anterior fibres of the trapezius arising from the deep surface of the anterior part of the carapace, and tbese fibres form the cephalo-humeral. The posterior part of the muscle rises from the fourth cervical to the last thoracic spines and is inserted into the scapular spine. In Chlamydophorus the anterior part of the muscle is separated from the posterior by a cellular interval, the anterior fibres, as in Dasypus, arising from the head-shield. In Tatusia no mention is made of an origin from the carapace. In the Manidce the cephalo-humeral is Avell marked and rises from the occiput (29, 31, 32, 33, 34). The remainder of the muscle forms one mass and is inserted into the spine of the scapula and its acromion process. In Oryeteropus (35, 36, 37) the origin is from the occiput, ligamentum nuchas, and anterior nine or ten thoracic spines, the insertion is into the spine and acromion process of the scapula, but there is apparently no clavicular bundle or cephalo-humeral muscle. Latissimus dorsi.-This muscle has the ordinary origin from the posterior half of the thoracic spines, the lumbar fascia, and three or four posterior ribs, and is inserted, as usual in mammals, into the humerus below its neck. In the Dasypodidce it is remarkable for rising from more ribs than usual, often from the third or fourth to the last. These costal origins blend with the deep part of the insertion of the pectorals, and form a muscular floor to the axilla. W e regard them as unusually well-developed achselbogen, |
