NATURAL HISTORY OF SLIPPER-LIMPET. 441 



The young male individuals creep about from place to place, and 

 eventually settle down either on shell or some similar surface, or on 

 the end of a chain. Suppose an individual to settle on an oyster 

 shell. The young male grows larger, and at the same time the edge 

 of its shell takes on the contour of the surface to which it is attached, 

 so that they fit accurately together. As the individual increases in 

 age, it begins to change into a female, but meanwhile another young 

 male may creep on to its back and settle down. This latter individual 

 in turn begins to change into a female, another young male in the 

 meantime having crept on to its back. With a repetition of this 

 process, longer and longer chains are formed, until in odd cases as 

 many as thirteen individuals may be found in chain. In this way it 

 will be seen that in any chain the bottom individuals will be females, 

 and the end individuals males, while between these may occur 

 individuals of all intermediate sex forms between male and female. 



Eegarding, therefore, the fact established that Crepidula is prot- 

 andric, the occurrence of a graded series of sex forms from the outer 

 to the attached ends of the chains is further evidence that the chains 

 are permanent. 



With regard to the age of chains, I have not yet finished my investi- 

 gations, but judging from reports I have received from different 

 stations along the Essex coast, it would seem that the number of 

 individuals in a chain will give also the number of years the chain is 

 old. The longest chains contain about as many individuals as j^ears 

 have elapsed since the first appearance of the species. Thus, at West 

 Mersea, the longest chains are composed of thirteen or fourteen indi- 

 viduals, and I estimate that Crepidula would first appear on those 

 grounds about fourteen years ago. Local fishermen will almost 

 certainly underestimate the length of time Crepidula has been 

 present in their locality. 



With regard to the destruction of Crepidula on the oyster grounds, 

 it does not seem at all possible to make any sweeping attack on this 

 pest. However, an attempt might be made to make Crepidula saleable 

 by trying various methods of cooking it to make it palatable. In this 

 way Crepidula might come to be rather a desirable acquaintance than 

 an enemy. There would appear to be every likelihood of Crepidula 

 being equal in value to the common AVhelk as an article of food. But 

 -no doubt the animals should be taken out of their shells before being 

 cooked. After a little practice it is quite easy to take the animal out 

 whole. Fishermen at West Mersea say that Crepidula eats rather 

 tough and bitter, but I was told the limpets were cooked in their shells, 

 so that a good result could not be expected. 



NEW SEKIES. — VOL. IX. XO. 3. JUNE, 1912. 2 F 



