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Show 242 MR. G. E. DOBSON ON CAPROMYS MELANURUS. [Apr. 1, Interossei dorsales.-These muscles are fused with the palmar interossei (flexores breves) throughout their muscular extent. Of the pair of flexores breves for each of the three middle digits, each muscle sends a long tendon forwards and dorsalwards alongside each digit to unite with the tendon of its fellow passing along the other side of that digit over the base of the second phalanx of the same digit into which it is inserted, crossed by the tendon of the long extensor going to the terminal phalanx. Thus each of the three middle digits of the manus has a pair of dorsal as well as of palmar interossei tendons. The fifth digit, however, has but a single interosseous tendon, and the small pollex appears to have none. Muscles of the Hind Limbs. Gluteus maximus is wide but thin, arising from the anterior extremity of the ilium and from the spinous processes of (he sacral and coccygeal vertebrae, and is inserted into the fascia lata of the thigh and into the lower external third of the shaft of the femur. Gluteus medius is of great size. It arises from the spines of the sacral and coccygeal vertebrae under cover of the gluteus maximus and from the greater part of the upper surface of the ilium, including within the fold thus formed the small gluteus minimus; the fibres are inserted by two short and thick tendons into the upper and lower sides of the greater trochanter. Gluteus minimus (included as above described) is a narrow long muscle arising from the upper and inner part of the anterior half of the ilium, and from the sacrum, along with the gl. medius, forms a flat tendon inserted into the greater trochanter between the two tendons of the gl. medius. Pyriformis and obturator internus are both absent. Quadratus femoris arises under cover of the adductor magnus from the tuber ischii, and is inserted into the outer side of the lesser trochanter. Gemelli appear to be united, forming a broad flat muscle arising from the whole length of the ischium from the acetabulum to the tuber ischii and inserted into the greater trochanter under cover of and below the gl. medius. Biceps flexor cruris arises by two heads, a superficial and a deep: the former from the transverse processes of the last two coccygeal vertebrae ; its fibres pass outwards under cover of the ilio-caudarl muscles, overlying the great sciatic nerve, and are inserted into the head of the fibula and into the fascia covering the knee-joint; the deep head arises from the tuber ischii in connexion with the adductor magnus by a narrow tendon, and, spreading out into a fan-shaped muscle, is inserted above in connexion with the tendinous aponeurosis of the superficial part into the head of the fibula, and, lower down, into the fascia covering the peroneal muscles and into the tendo-achillis. The sartorius is not represented. |