THE EGG MASS OF LITTORINA OBTUSATA AND LACUNA PALLIDULA (GASTROPODA : PROSOBRANCHIA)

The egg masses of Littorina obtusata and of Lacuna pallidulahave been compared with regard to size, shape, egg number, eggsize and substratum. The structure and histochemistry of thespawn of the two species has been investigated and observationson the laying process in L. obtusata are also recorded. ^* Present address: Portway School, Penpole Lane, Shirehampion,Bristol, BS11 0EB. (Received 12 October 1977;