STUDY X. 385 



plants, like fruit growing upon them. I likewife 

 found there the Venus-lhell, completely white, 

 with a rofe-coloured mouth, fwelled backward 

 like eggs, from which too they fometimes borrow 

 their name. But it is now impoflîble for me to 

 affirm, with certainty, whether they adhered to 

 the dark coloured rocks, or to the white madre- 

 pores. 



There are likewife to be found, on the coafts of 

 Normandy, in the diftriâ: of Caux, two forts of 

 rocks, the one of white marl, detached from the 

 cliffs, the other formed of black bifets, which are 

 amalgamated with the craggy cliff. Now, 1 never 

 faw there, in general, but two forts of periwinkles, 

 called by the country people vignots, the one very 

 common, and ufed as food, which is quite black, 

 and the other white, with a faint-red mouth. I 

 prefume not, at this diflance, to aver, whether the 

 white periwinkles attach themfelves to the white 

 rocks, and the black periwinkles to the black 

 rocks, or contrariwife, for I did not make the ob- 

 fervation. But whether they form with thofe 

 rocks confonances or contrafts, it is very fingular 

 that, as there are but two fpecies of rocks, fo there 

 (hould be but two fpecies of periwinkles. I am 

 inclined to believe, that the black periwinkle ad- 

 heres, in preference, to the black rock -, for I have 



VOL. II. c c obferved, 



