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Show 1896.] ANATOMY OF PETROGALE XANTHOPUS. 699 border into the cartilages of the second, third, and fourth ribs. It has a few indistinct intersections. The Pyramldalls rises from the inner side and tip of the marsupial bone, and from the fascia over the lower part of the rectus. About midway between the pubes and xiphoid it blends with the linea alba. The Supracostalls rises from the sternal ends of the cartilages of the 3rd, 4th, and 5th ribs, and is inserted into the first rib just external to the attachment of the rectus. It is well marked, and continues the plane of the external oblique, lying between the rectus and the pectoral. Tbe Quadratus lumborum is present, but is extremely difficult to separate from the erector spinae. The Psoas parvus is very large, and rises from the bodies of all the lumbar vertebrae except the last; it is inserted into the prominent ilio-pectineal eminence. The Psoas magnus is smaller than the last, and rises from the transverse process and side of the body of the last lumbar vertebra, as well as from the anterior part of the sacrum ; it joins the iliacus to form a very broad ilio-psoas, which is inserted into the flat lesser trochanter. Muscles of the Tail. These muscles are by no means easy to distinguish one from the other, but the following seems the most satisfactory division. The Extensor caudce externus rises from the accessory processes of all the lumbar vertebrae, from the sacrum, and from the caudal vertebrae nearly as far as the middle of the tail. The tendons, which are very long, are inserted into the transverse processes of the caudal vertebrae, those which rise most anteriorly being inserted first. Meckel1 describes this muscle as being distinctly divided into two in the Kangaroo, but I was unable to make out the division satisfactorily. The Extensor caudce Internus is fleshy, and rises from the spines of the sacral and caudal vertebrae; short tendons pass to the transverse processes of the vertebrae close behind. The Abductor caudce externus rises from the ischium, and is inserted into tbe transverse processes of the 5th, 6th, and 7th caudal vertebrae. The Abductor caudce Internus is simply a continuation of the intertransversales muscles. The Flexor caudce externus comes from the ventral surface of the sacrum and tail, and is inserted into the ventral surface of the transverse processes by long tendons, which are arranged in the same manner that was noticed in Sphlngurus'-that is to say the most superficial tendons are first inserted, and the deeper ones. reach the surface rouud the inner side of these. 1 'Anatomie comparee,' vol. vi. p. 177. 2 " Myology of Rodents," P. Z. S. 1894, p. 279, 45* |
