. The biology of the amphibia. Amphibians. 256 THE BIOLOGY OF THE AMPHIBIA The hind limbs also were held astraddle when at rest, and a dorsal and a ventral group of muscles could be inferred in the early tetrapods. The limb muscles have presumably split from the hypaxial musculature during phylogeny, but modern Amphibia show no evidence of such origin in their ontogeny (Lewis, 1910; Rylkoff, 1924). The musculature of fore- and hind limbs was not alike in detail even in the most primitive tetrapods. Such a difference was correlated with the different structure of the pectoral as compared with t
. The biology of the amphibia. Amphibians. 256 THE BIOLOGY OF THE AMPHIBIA The hind limbs also were held astraddle when at rest, and a dorsal and a ventral group of muscles could be inferred in the early tetrapods. The limb muscles have presumably split from the hypaxial musculature during phylogeny, but modern Amphibia show no evidence of such origin in their ontogeny (Lewis, 1910; Rylkoff, 1924). The musculature of fore- and hind limbs was not alike in detail even in the most primitive tetrapods. Such a difference was correlated with the different structure of the pectoral as compared with the pelvic girdle inherited from. Fig. 95.—Dissection of the arm and shoulder musculature of Megalobatrachus. , M. anconeus lateralis; , M. anconeus scapularis; bri., M. brachialis inferior; cbl., M. coracobrachial longus; , M. deltoides scapularis-dorsalis scapulae; , M. extensor carpi radialis; , M. extensor carpi ulnaris; , M. extensor digitorum longus; lev. scap., M. levator scapulae; Id., M. latissimus dorsi; p., M. pectoralis; , M. procoracohumeralis; , M. serratus profundus; spc, M. supracoracoideus; sup. long., M. supinator longus; trap., M. trapezius. (After Miner.) fish. Further, the forelimbs were early used to raise the body, while the hind limbs pushed it forward. In correlation with this functional difference, the elbow joint formed in the forelimbs tended to be directed backward like that of modern Amphibia, while the knee joint gave a better purchase when directed forward. This functional difference, continued in phylogeny, affected the distal segments least and a great similarity may still be found in the distal muscles of the fore- and hind limbs of modern salamanders such as Necturus (Wilder, 1908). Although the pelvic girdle very early in the history of the first tetrapods gained a firm attachment to the vertebral column, the pectoral. Please note that these images are ext
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