SPAWN OF EOLIS. 45 



back into the shell, and the foot being drawn down, 

 brings along with it the operculum, which closes the 

 orifice. But when in action, the whole of these parts 

 project beyond the opening of the shell, the foot lying 

 back against the spire ; and the oral lobes inclining 

 forward, their cilia commence to vibrate, and the larva, 

 with the mouth of the shell upwards, moves through 

 the water with lively action, sinking or rising, or ad- 

 vancing onwards at its pleasure." l 



The fecundity of these mollusca is immense. An Eolis 

 papillosa of moderate size in one of my aquaria, de- 

 posited successively nine strings of spawn between 

 March 20th and May 24th. The strings were exactly 

 alike in length and arrangement; each comprised 

 about 1 05 convolutions, and each convolution 200 

 eggs, while each egg contained on an average two 

 embryos. Thus the astonishing number of 378,000 

 embryos proceeded from this one animal in about 

 two months. 



Step by step we have crept along the beach, turning 

 stones as we went, till we are come to the great masses 

 of sandstone rock. Here are the Purples 2 by hundreds, 

 with their strong massive shells, some of them pure 



1 Alder and Hancock (DoEis). 



8 Purpura lapillus, sometimes known as the Dog-winkle. Three in- 

 dividuals, representing the varieties of colour, are seen in the middle of 

 Plate v., and a cluster of their egg-capsules in the lower left corner. 



