ABSTRACT
Artificial fertilization of the eggs of P. inaequivalvis has been carried out and the development followed to the dissoconch stage.
The development is very rapid and metamorphosis occurs in less than 4 days. The veliger spends less than one day in the plankton and this is the first record of a short-lived planktotrophic lamellibranch larva. The speed of development is related to the relatively large (105– 125 μ diameter) size of the egg and its contained food reserves. There is minimal dispersal of the young from the very localized habitat of the adult.
No protonephridia or larval eyes are developed and the gut follows a simple course in comparison with other lamellibranch larvae. The gills do not develop until after metamorphosis and the large palps and foot produce the ciliary currents connected with respiration, feeding, and cleansing between the loss of the velum and the development of the functional gill.
Unless otherwise stated all measurements are the maxima recorded.
The original primary somatoblast ≡ 2d has probably by this time divided 4 times giving four (x1—x4) small somatoblast cells (see Lillie, 1895).
