. The biology of the amphibia. Amphibians. 60 THE BIOLOGY OF THE AMPHIBIA elucidating the relationships of various genera. For example, Protopipa and Pipa are the only frogs which carry their eggs in individual dermal chambers on the back of the female parent and are un- doubtedly closely allied. Similarly, Phyllobates and Dendrobates, which until recently were placed in separate families, are the only genera which transport their tadpoles on the back of the male parent to streams where they com- plete their metamorphosis. The South American tree frogs, Cryptobatrachus, Hemiphractus, Gastrothe
. The biology of the amphibia. Amphibians. 60 THE BIOLOGY OF THE AMPHIBIA elucidating the relationships of various genera. For example, Protopipa and Pipa are the only frogs which carry their eggs in individual dermal chambers on the back of the female parent and are un- doubtedly closely allied. Similarly, Phyllobates and Dendrobates, which until recently were placed in separate families, are the only genera which transport their tadpoles on the back of the male parent to streams where they com- plete their metamorphosis. The South American tree frogs, Cryptobatrachus, Hemiphractus, Gastrotheca, and Amphignathodon, have been variously relegated by herpetologists. Since they are the only frogs which carry their eggs in a single mass on their backs (Fig. 20), whether or not this mass is exposed or covered by a fold of skin forming a veritable sac, it appears probable that they are closely allied. This conclu- sion is supported by the fact that all the larvae have distinctive bell-shaped gills (Fig. 21 B-C). Many other frogs lay their eggs out of water and yet the larvae of none of them have bell- shaped gills. Many frogs and toads lay their eggs in the water and the polliwogs which emerge. Fig. 20.—The evolution of the dorsal brood pouch of the Hylidae. A. Gastrotheca marsupiata, the purse-like brood pouch cut open on the side to show the eggs within. B. Gastrotheca pygmaea, female with the eggs removed from the widely open brood pouch. C. Cryptobatrachus evansi, female with Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Noble, Gladwyn Kingsley, 1894-1940. New York : McGraw-Hill
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