. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 378 MONOTREMATA. supporting the innermost digit or pollex, the trapezoides (g), the index, the os magnum (f), which is almost the smallest, sustaining the medius, and the unciforme (e) the two outer digits: this description is taken from the Echidna: the only essential difference obser- vable in the Ornithorhynchus is the contribu- tion by the os magnum of a greater share to the articulation with the ring-finger. In the Echidna all the bones of the fore- extremity are relatively larger and stronger than in the Ornithorhy
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 378 MONOTREMATA. supporting the innermost digit or pollex, the trapezoides (g), the index, the os magnum (f), which is almost the smallest, sustaining the medius, and the unciforme (e) the two outer digits: this description is taken from the Echidna: the only essential difference obser- vable in the Ornithorhynchus is the contribu- tion by the os magnum of a greater share to the articulation with the ring-finger. In the Echidna all the bones of the fore- extremity are relatively larger and stronger than in the Ornithorhynchus, but this dif- ference is especially remarkable in the meta- carpal bones and two first rows of phalanges Jig. 176, h, i, /c), which are singularly short, broad, and thick. The palm is strengthened by two large sesamoids developed in the flexor tendons in the Echidna; these are sometimes confluent (Jig. 175, /). The number of pha- langes in both Monotremes is the same as in other Mammals, viz. two to the thumb and three to each of the fingers. This is not the case in any Saurian, and the retention of the Mammalian type at the peripheral segment of the limb, with the singular deviation from it at the central supporting arch, is not one of the least remarkable points in the osteology of the Monotremes. There is a sesamoid bone at the palmar aspect of each of the distal articulations of the phalanges in the Echidna (fig. 175), and at all the digital articulations in the Ornithorhynchus (Jig. 173, u, d). Fig. in the Ornithorhynchus; the pelvis of the Echidna resembles that of Birds in the perfo- ration of the acetabulum (Jig. 177, g), but the pelvis in both Monotremes chiefly resembles that of the higher implacental Mammalia in the presence of the marsupial bones. Fig. 177. Bonet of the fore-foot, Echidna hystrix. ( Cuvier.) The ungual phalanges are long, depressed, nearly straight, of great strength in the Echidna, in which each of them is perforated at the palmar asp
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