JOURNAL OF CONCHOLOGY, VOL. II, NO. I, JANUARY, I9O4. I5 



Isaac Thompson was not, however, a mere speciaHst among minute 

 Crustacea; he was a naturaUst of extensive knowledge and broad 

 sympathies. In conjunction with his friend Dr. Herdman, he took 

 an active part in the foundation and subsequent management of the 

 Liverpool Marine Biology Committee, founded for the systematic 

 investigation of the fauna of the district. He filled for years the 

 important office of treasurer, watched over its small beginnings 

 in the Marine Laboratory on Puffin Island, and eventually saw it 

 installed in more commodious premises at Port Erin. 



He was also an original member of the Liverpool Biological Society, 

 and was recently elected to its Presidential Chair. His interest in 

 science was, however, even wider than that of the naturalist pure and 

 simple : he had a sympathy with, and understanding of, the problems 

 of physical science, and was one of the founders of the Liverpool 

 Physical Society. 



But he was more than a scientist : he was intensely human in all 

 his thoughts and feelings ; full of warm sympathetic interest in all 

 that concerned the welfare of his fellow-men. In him we have lost at 

 one blow the earnest student of nature, the sound financier, the active 

 clear-minded administrator, the sympathetic neighbour, and the true- 

 hearted comrade. What wonder, then, that his friends and colleagues 

 feel the loss a heavy one. 



Fish and their relation to Paludestrina jenkinsi. — It has for sometime 

 been a noticeable fact that where Paludestrina jenkiusl occurs it is generally in great 

 abundance. It has also been stated to have "taken over" a locality, to the 

 exclusion of other shells, but I do not remember having seen any reason assigned for 

 this. Some little time ago I was able to obtain a fair quantity of this shell and deter- 

 mined to watch the effect of its introduction among various fish, and the result of the 

 experiments may be worthy of notice. This shell I find cannot exist in the presence of 

 Carp even if kept constantly supplied with other food. My previous experience in 

 regard to Carp is that they will let shells of any sort alone if well fed, even Liiniiiea 

 feregra escaping. In one aquarium there are two rather fine Perch with which I 

 have been unable to keep any shell, including even Paludina contecia. Paludestrhuz, 

 however, moved about unmolested. If starved a little the Perch will take this 

 mollusc, but I noticed that the shells appeared again in the excreta unbroken. My 

 later experiments with Roach and Dace go to prove that they will take the shell 

 occasionally if hungry, but do not search for it like the Carp. It seems likely then 

 that the absence of Carp may have a great deal to do with the spread of this shell. 

 But experiments with fish in confinement are by no means conclusive ; records 

 should be made of the fish inhabiting the localities where this shell is taken. The 

 young of Paludina contecia are unmolested by Carp and Dace, but killed by Perch, 

 Minnow and other fish. It would be interesting to find out which fish allow 

 the Paludestrina to breed unmolested, and whether Carp are present in a locality 

 spoken of as "taken over" by this little mollusc. — J. D. Dean (Read before tlie 

 Society, January 14, 1903). 



