| OCR Text |
Show 1896.] MYOLOGY OF RODENTS. 175 that muscle on the inner side of the opening, while the pouch itself is deep to the whole of the panniculus, in the latter the Fig. 9. Pouch-muscles of Heteromys. pouch is formed by an evagination of the buccinator, to the fundus of which a slip of platysma has become attached. Latissimus Dorsi.-This muscle has the same attachments that it possesses in other Rodents ; the dorso-epitrochlearis is always present, and reaches as far as the olecranon, though in Cricetomys it is also inserted into the fascia of the forearm. Trapezius.-In most of the Myomorpha as in the Sciuromorpha there are three separate parts of the trapezius. The first of these, described by Milne-Edwardsl and by Strauss-Durckheim as the clavo-cucullaris, consists of the fibres passing between the occiput and the clavicle ; it is separated from the rest of the muscle by the levator claviculae, and was found in the following animals:- Myoxus, Cricetus, Cricetomys, Microtus, Myodes, Mus decumanus, Heteromys, Bathyergus, and Siphneus. In Georychus and Mus barbarus, however, this part of the muscle was not seen. The second part, or acromio-cucuharis, consists of the fibres running between the ligamentum nuchae and the anterior thoracic spines on the one hand, and the acromial process and spine of the scapula on the other; it is usually separated from the third part or dorso-cucullaris by a pad of fat. In all the animals dissected, these two parts were separate with the exception of Cricetomys and Myoxus. Rhomboidei.-The rhomboideus capitis is a distinct muscle, while the major and minor are not separable one from another. In Cricetus, Myoxus, Microtus, Georychus, Bathyergus, and Heteromys, part of the rhomboideus capitis rising from the outer part of the occipital curved hne is separated from the rest and runs to the inner half of the spine of the scapula, covering part of the supra-spinatus instead of going to the vertebral border. Serratus Magnus and Levator Anguli Scapulce.-The origins of 1 ' Etudes pour servir, &c.,' p. 94. |
