178 



BUCCTNUM. 



also called ' Sea wash-balls,' because of" tlieir being used instead 

 of soap hy sailors to wash their hands (tig. 312). Dr. Johnston 

 compares this vesicular mass to the nest of the humble-bee. It 

 is composed of numerous cartilaginous pouches, of the shape and 

 size of a large split pea, piled irregularly- one upon another, and 

 attached by their edges at the base. Cailliaud counted 544 of 

 these cells in one of the spawn-masses. I]ach cell contains at 

 first several hundred eggs, which are afterwards so greatly re- 

 duced in number that only from fifteen to thirty fry come to 

 maturit}'. The process b}' which this redaction takes place has 

 been disputed by Scandinavian and English physiologists, not 

 less as to Bticcinum than with respect to Purpura. Koren and 

 Danielssen state that the eggs are first spherical, that they after- 

 wards separate into distinct portions, and then amalgamate or 

 agglomerate and assume a diiferent shape. Sir Jolm Lu])bock, 

 on the contrary, ascertained that the more advanced embryos 

 swalloAv the other yelks whole, and in such quantities as to 

 become greatly distended ; his paper in the ' Report of the British 

 Association ' for 18(')0 contains a representation of ' a young- 

 embryo in the act of swallowing an egg' (figs. 306, 307). l>r. 

 Mcintosh observed two specimens of the variety littoralii^, on 

 the 19th of October, 18()3, in tlie act of depositing spawn under 

 a stone, about mid-tide, in a rock-pool at St. Andrews. An egg- 

 case, extruded from one of these whelks which he held in his 

 hand, was quite soft, and fell into the water like a ball of jelly. 

 Before the fry leaves its cell, it is furnished with two rounded 

 and ciliated lobes in front, a proboscis, eyes, foot, gills, heart, 

 otolites or ear-stones, and other organs, besides a perfectly formed 

 shell of two whorls and an operculum. The spawning season 

 takes place according to the latitude and climate, between 

 October and May ; about two months are required for the devel- 

 opment of the fry. The shi'lls vary exceedingly in thickness ; 

 some are solid and coarsely ribbed ; others are thin, and their 

 sculpture is ver}' delicate. Sometimes the top of the shell is 

 broken off, and the opening is closed Ijy a plug. In young speci- 

 mens the nucleus of the operculum is more central than in tlie 

 adult, the lateral extension of growth ))eing inwards or towards 

 the pillar. Mr. Dennis and Mr. Norman believe that the scalari- 

 forin distoi'tion of the whorls, whicli is not unfreciuent, is occa- 



