THE ONTOGENETIC DEVELOPMENT OF THE HINGE IN SOME SPECIES OF BLACK SEA BIVALVED MOLLUSKS |
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| Abstract: | Most previous studies are found to be lacking in that they deal only with the larval stages and fail to trace the hinge development throughout its changes to the adult form. The present writer is concerned with material from the Black Sea. Large suites of specimens were available for most of the 27 species studied so that the author was able to trace the changes in hinge structure with the growth of the shell from larval to adult size. Three lines of hinge development, namely Anisomyaria, Heterodonta, and Desmodonta, are examined. Anisomyaria is represented by the families Mytilidae and Ostreidae. With the Heterodonta two lines of development are recognized in the species studied, the cyrenoid type of hinge development, shown by members of the family Veneridae, and the lucinoid type, shown by examples from the Lucinidae, Tellinidae, Scrobicularidae, Doncidae, Cardiidae, Mactridae, and Dreissenidae. The family Corbiculidae is representative of the Desmodonta. Bernard's system of naming the teeth of the heterodont hinge was found to be applicable to the cyrenoid type of hinge, but in a number of cases did not give a true picture of the origins of certain of the teeth of the lucinoid type of hinge. The ontogenetic development of various features used as criteria to characterize superfamilies, families, genera, and species of the 27 species examined is presented in tabular form. Developmental stages of the cyrenoid and lucinoid types of heterodont dentition are illustrated.--F. J. E. Wagner. |
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