SHELL AND HINGE DEVELOPMENT OF YOUNG CORBICULA-FLUMINEA (MULLER) (BIVALVIA, CORBICULOIDEA)

Small specimens of Corbicula fluminea (Muller) were collected as juveniles newly released from adults, and larger specimens were extracted from sediment taken from natural beds of adults. Lengths of the prodissoconch I averaged 196.9 +/- 6.7-mu-m (xBAR +/- SD; range = 187-213-mu-m; n = 17); the average length for the prodissoconch II was 233.3 +/- 5.0-mu-m (range 228-244-mu-m, n = 10). The dissoconch had strong commarginal sculpturing, with less prominent radial striae also present. A ligament pit occurred in the posterior region of the shell hinge. Three cardinal and two lateral teeth developed, and shell tubules were noted in the early dissoconch.