The psoas snagnus and iliacus internus form a single muscle, having the usual origins, and inserted by a common tendon into the large internal condyle.
The gluteus externus is larger than is usually the case with quadrupeds; its tendon is inserted into the plantar fascia and the bone which sup ports the spur. The gluteus niedius, gluteus intern us, pcctincus (45), biceps flexor cruris, gracilis (34), sertorius (35), reaus femoris (36), adductores fernoris (46), semitendinosus (47), sconintembranosus, vast us externus, offer no notable deviations from the usual structure. A strip of fibres (49) descends from the gracilis to the sphincter avocet (II). A muscle, called by Meckel flexor accessorius a caudil ad tibiam tendens' (51), arises from the transverse pro cesses of the anterior caudal vertebrae, and converges to be inserted into the tibia. Another peculiar adductor of the leg, which might be termed ' intertibialis ' (52), is attached by its extremities to both tibia:; its fleshy belly passes across the sphincter cloaca (II), and is connected with a strip of the panniculus carnosus (i).
The gastrocncinius (48) derives its largest origin from the produced and expanded head of the fibula, and its smaller belly from the internal femoral condyle; its tendon is implanted in the calcaneum. The analogy between the gastro cnernius and ulnaris internus is strikingly illus trated in the Ornithorhynchus.
The coleus arises from the head of the fibula and from a large proportion of the tibia ; it is nowhere blended with the gastrocnemius, but is inserted by a thick and short tendon into the astragalus.
The abductors of the outer digits of both the hand and foot are well developed for the purpose of expanding the web which connects the toes.
In the figure the following muscles of the leg are shown, viz. 37, tibialis enticus, 38, ex tensor Itallecis longus, 39, peronaus longus, 40, perone'us brevis, 41, extensor digitoruns communis przfundus, brevi analogus, 42, exten sor digitoruns communis sublimi.s, 43, a portion of the same muscle corresponding with the indicator of the fore leg, 44, exansor digiti quinti accessories.