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Show 244 MR. G. E. DOBSON ON CAPROMYS MELANURUS. [Apr. 1, Adductor brevis (fig. 3, a. b) is very large, arising from the symphysis pubis and ramus of the pubis and ischium as far as the tuber ischii; it forms a thick and broad muscular mass inserted along nearly the whole length of the shaft of the femur in its middle third under cover of the insertion of the adductor longus, and in its lower third extending to the insertion of the adductor magnus. Adductor magnus (fig. 3, a. m), long and narrow, arises from the tuber ischii under cover of and in connexion with the deep head of the biceps flexor cruris, and passes forwards, separated from this muscle by the great sciatic nerve, to its insertion into the femur immediately above the point of origin of the internal head of the gastrocnemius, with which it is slightly connected. Adductor quartus is large, covering the obturator externus; it arises from the lower and part of the posterior and anterior margins of the obturator foramen under cover of the adductor brevis and adductor longus, and is inserted into the shaft of the femur immediately below the lesser trochanter and between it and the insertion of the adductor brevis. Pectineus (fig. 3, p) arises above the adductor longus from the margin of the pelvis below and behind the acetabulum, and is inserted into the middle third of the shaft of the femur, in front of the adductor longus. Semi-membranosus (fig. 3, s.m) arises from the ramus of the pubis and the ischium, behind the adductor brevis, and is inserted behind the internal lateral ligament. Semi-tendinosus (fig. 3, s.t) arises by two heads-one small, from the tuber ischii immediately above the semimembranosus, and in connexion with the biceps flexor cruris ; the other from the last coccygeal vertebrae and the side of the base of the tail; the anterior part of the latter unites with the posterior margin of the deep head of the biceps flexor cruris, the posterior part with the deep head described above arising from the tuber ischii, and is inserted below the gracilis into the shaft of the tibia. Psoas parvus is small, arising from the first to the fourth lumbar vertebrae, and inserted tendinously into the margin of the pelvis. Psoas magnus, much larger, arises further backwards from the bodies of the third to the last lumbar vertebra, close to its fellow of the opposite side ; unites with the iliacus, and is, with it, inserted into the lesser trochanter. Obturator externus arises under cover of the adductor quartus from the margin of the obturator foramen and from the obturator ligament, and, forming a thick muscular tendon, is inserted into the neck of the femur. Extensor digitorum longus arises by a tendon from the external condyle of the femur, and, passing down under cover of the tibialis anticus, enters the foot, and is distributed to the four outer toes. Tibialis anticus is very large, arising from the head of the tibia, from the upper half of that bone, and from the interosseous ligament; it forms a thick tendon which curves round the side of the foot, and, passing under cover of the abductor ossis metatarsi hallucis, is inserted |