抄録
The distribution patterns, sizes and nucleation sites of aggregated prisms on the outer shell surface were examined in 16 species of Bivalvia and modeled theoretically. Biometric analysis shows a negative correlation between the median size and variation of sizes of calcitic simple prisms. In species with aragonitic vertical composite prisms, instead, the density of prisms tends to decrease when their nucleation sites are randomly distributed. Comparison of the results of computer simulations with those of biometric analyses reveals the following : 1) a positive correlation between growth rate of prisms and the probability of nucleation for simple prisms, and 2) a limit of the number of nucleations per unit time in vertical composite prisms. Prism size correlates with the growth rate of the entire shell or prisms, and increases as the shell grows faster or prisms grow slower.
