MARSHALL: ADOITIOKS TO "BRITISH CONCHOLOGY. ' 213 



According to Mr. Orton, who has examined its natural history, 

 " it is a protandrous hermaphrodite," which being interpreted in un- 

 scientific language means that it is first male and then female. 



Ci-epiduloi are very prolific, and have multiplied in a marvellous 

 manner on our oyster beds since they were first noticed. Their pro- 

 geny in the larval stage, like that of many other species, are free 

 swimming, and so capable of rapidly spreading. 



They have crossed the Atlantic on American oysters, and when laid 

 down in British waters have combined to rob the Britisli " native " of 

 its legitimate food. This was becoming so serious that the Kent and 

 Essex Fisheries Commission, as well as the Oyster Merchants' Asso- 

 ciation, directed attention to the advisability of destroying all the 

 so-called " American limpets '' that might be caught, owing to the 

 damage and destruction done to the fisheries. They assert that these 

 limpets intercept a great deal of the oysters' food, and were becoming 

 a nuisance to the oyster industry generally. So an edict went forth 

 that all American limpets were to be ruthlessly exterminated. 



At recent meetings in London of these authorities it was reported 

 that the measures taken to prevent the increase of these limpets had 

 been successful, though costly. At Colchester during 1912 over one 

 hundred tons of the limpet debris had been brought ashore and dis- 

 posed of, and although this had cost a great deal of money, a serious 

 peril to the oyster trade of this country had probably been averted in 

 time. 



At a conversazione ot the Royal Society, held on May 8, 1912, the 

 Marine Biological Society exhibited an interesting colony of the 

 Creptdula, or " slipper limpet," which, on account of the difficulty of 

 watching them feed under cover of their shells, had been induced to 

 attach themselves to plates of glass, and then fed with specially pre- 

 pared food of a scarlet colour, when they could be observed daintily 

 selecting the finer morsels to feed upon, and rejecting the coarser 

 particles for the oysters. 



(To be continued). 



Two hitherto unnoticed varieties of Helicella heripensis Mab. — When 

 collecting H. heripensis at Princes Risborough in Buckinghamshire, I found very 

 plentifully a white form with strong black-banding, entirely analogous to the var. 

 ornata of H. caperata. I would suggest that the analogy be followed and the 

 varietal name ornata adopted for this form, which occurs on the ridge of the Chiltern 

 Hills. At E. Fleet and at Coryates in Dorsetshire, I have taken a deep chocolate 

 form of the same species, which might be known as var. Jitlva from the corresponding 

 form oi H. caperata. — J. E. A. JoLLlFFE {Read before the Society, May 13th, 1914). 



