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Show 1866.] ON THE ANATOMY OF THE CRESTED AGOUTI. 411 Gluteus medius. G. min. Gluteus minimus, II. Iliacus. Sc. Scansorius. • R.f. Eectus femoris. T. v.f. $ G. max. Conjoined tensor vagina; femoris and gluteus maximus; the tendinous part continuous with the lumbar fascia is removed to exhibit the deeper muscles. B. Biceps. Q.f. Quadratus femoris. S.t. Semitendinosus; and lower down the same letters apply to its fascia continued towards the ankle. T. q. e. Tendon of combined quadriceps extensor going to patella. T. a. Tibialis anticus. P. I. Peroneus longus. P. q. d. Peroneus quarti digiti. E. I. d. Extensor longus digitorum. E.p. h. Extensor proprius hallucis. In. Interossei. So. Soleus. &«. Gastrocnemius. P. Plantaris. F. 1. d. Flexor longus digitorum. F. I. h. Flexor longus hallucis. A. Anal opening. A. g. Anal gland. In the Hare and Rabbit the rectus is much less in size than the vastus externus, but about equal to the vastus internus. The crureus covers the front of the femur as high as the surgical neck. This muscle is very large and most unusually distinct in all the four Rodents. What we take to be the adductor magnus, by reason of its insertion, is a long and narrow muscle, in appearance not unlike an adductor longus as it exists in M a n and some Quadrumana (fig. 4, A. mag.). It has origin by a narrow strongish tendon from the ischium towards the posterior extremity of the pubic symphysis, and has an insertion by tendon into the top of the lowest third of the shaft of the femur at its back. The deep femoral artery passes over this muscle ; so that no Hunter's canal exists, except what is formed by the fibres of the semimembranosus. The Guinea-pig agrees most nearly with the Agouti. In the Rabbit and Hare the adductor magnus is broader and more fleshy, it has also a larger insertion into the shaft of the femur. Adductor longus'"and brevis (fig. 4, A. I. $• br.). These, at their origin from the symphysis pubis and brim of pelvis, form but one ^k mass, and so proceed to the femur. At their insertion into the back of the bone, extending from its head to about the middle of the shaft, there is a very slight interval, indicative of separation; this partial division is denoted by glistening tendinous fibres of the upper and larger portion of the muscle. In the Hare and Rabbit these muscles are equally fused together; but, on the other hand, they are more separated in the Guinea-pig. Tibialis anticus. Instead of its having, as is so often the case, a single origin and double insertion, this remarkable muscle has a double origin and a single insertion. The greater part arises by muscular fibres from the outer side of the upper fifth of the tibia and the head of the fibula. The smaller division arises by a very long and strong tendon from the front of the femur, on the outer condyle, just outside the rotular surface. The two portions become intimately united a little below the middle of the tibia, and are inserted by a quite single but exceedingly strong tendon into the proximal end of the metacarpal bone of the index of the foot, i. e. the inner toe (figs. 4 & 5, T. a.). It has the same peculiarities in the Guinea-pig*; but in the Hare * In one specimen of the Guinea-pig this muscle had but a single head. |
