OCR Text |
Show 1899.] THE MYOLOGY OF THE EDENTATA. 325 Cerv. Tr. Procs. Eibs. Cyclothurus (17) 2-7 1-8 (18) 5-7 1-7 (20) 5-7 1-7 (21) 5-7 1-7 Dasypus (22) hinder C. V. 1-8 or 9 „ (24) 5-7 1-7 Manis (29) 1-7 1-7 „ (30) 1-7 1-7 „ (32) 2-7 „ (33) 2-7 1-6 Oryeteropus (35) 2-7 1-8 (36) 2-7 1-8 (37) 2-7 1-8 5) 55 From the foregoing it will be seen that the neck portion of the muscle (the levator anguli scapulas of human myology) is either absent or feebly developed in the Bradypodidce. In Tamandua (14) and tAvo specimens of Manis (29, 30) it is described as arising from the atlas, but past experience makes us think that in these cases the rhomboideus profundus is incorporated Avith the serratus ventralis colli. In some cases, e. g. Cyclothurus, the cervical, anterior and posterior thoracic origins may remain distinct as far as their insertion, and the muscle may then consist of three portions, as it more or less does in Man. In other cases, e. g. Dasypus (22), the cervical and thoracic portions may form two separate sheets, while in many instances the whole muscle forms one continuous plane. It may be added that on the whole the muscle is one of great strength, exceeding in this respect the condition met Avith in most of the mammals examined by us, also that the scapular insertion often takes the form of tAvo strong bundles attached to a triangular portion of bone at the caudal and cephalic ends of the scapula respectively, the part between, though continuous with these two bundles, being comparatively thin. Pectorales.-The pectoral mass in Edentates, as, indeed, generally amongst the Mammalia, is exceedingly hard to classify, for the greater the amount of available material, the more difficult does the generalization become. W e feel that the only way to do justice to the subject would be to repeat the various descriptions in extenso; but as this is hardly possible, Ave shall content ourselves with making Avhat generalization we can. W e believe that a typical pectoral has superficial and deep manubrial and superficial and deep gladiolar planes, that there may be a clavicular portion and an abdominal sheet or pectoralis quartus arising from the linea alba, that one or more bundles may rise from the anterior rib3 deep to the gladiolar fibres, and that these may be described as a pectoralis minor. In Bradypus we have six descriptions, no two oafb dPwoRhmOiCcn haZ lO aOgpLroer. etS.io oncM -aoc1ra8 l9iasn9ty,et rNh ioan.ng dX rXMeIapIrc.eks iennttoisnhg afa ipleecdt o2tr2oal fisi nmidn aonr.y |