| OCR Text |
Show 848 MR. P. E. BEDDARD ON THE [Dec. 3, magnus, such as is figured by Ecker1 in Rana esculenta. The muscle ends in a thin rounded tendon, whose relations with the sartorius have been already referred to. Rectus internus, major et minor. In Rana and in Pipa there are two perfectly distinct recti interni ; in Xenopus there are also two. The larger of the two, which I take to be the major, overlaps the semitendinosus, and is overlapped by the minor. The latter lies entirely superficial to the major and covers its posterior half. O n the outer side of the thigh the only muscles visible without a dissection are the Semimembranosus and the outer part of the Triceps femoris. The Biceps is largely concealed by the vastus externus ; the great backward prolongation of the Latissimus dorsi- to which I have elsewhere2 directed attention as a point of resemblance between Xenopus and Pipa-completely covers the gluteeus and is attached to the thigh. The Gluteeus, after removal of the latissimus dorsi, is seen to be a very extensive muscle, much larger than in Rana. It is inserted by a flat tendon and also by muscle-fibre ; between its insertion and the head of tbe femur is to be seen a portion of the pyriformis, which is nearly but not completely covered by it. The Psoas is a fleshy muscle with a long insertion. In order to effectively display the pyriformis, the gluteeus must be removed or slit up the middle, and the two halves reflected. The pyriformis is then seen to be a large bipinnate muscle ending in a stout tendon, attached nearer to the head of the femur than gluteeus. § Affinities of Xenopus. The noteworthy peculiarities in the musculature of Xenopus as compared with Rana are :- (1) T h e large size and attachment of the Sartorius. (2) T h e single-headed Semitendinosus. (3) T h e enormous extension backwards of the Latissimus dorsi. (4) The absence of the Pedoro-cutaneus. (5) T b e attachment of the muscles covering the abdomen to the fascia covering the thigh. (6) T h e presence of a sheet of muscle below the Mylohyoid which joins the Deltoid. (7) The great extent of the Pectoral, which completely covers the Sternoradialis. (8) T h e large size of the Gluteeus. (9) T h e existence of a special muscle running from the ilium to the lung and oesophagus. There are also, as will be gathered from the foregoing account of the musculature of the animal, other differences from Rana of less importance. Of the differences enumerated above, (3), (4), (5), (6), and (9) 1 Loc. cit. p. 100, fig. 83, st'". 2 " On some Points in the Anatomy of Pipa americana," above, p. 834. |
