ON THE IRREGULAR GROWTH OF THE SHELL OE 

 THE COMMON LIMPET IN CONFINEMENT. 



BY JOHN E. ROBSON, F.E.8. 



Many years ago, when " The Aquarium " of the late Mr. Gosse 

 gave such an impetus to the study of marine life, I became smitten 

 with the prevailing fashion and determined to commence an Aqua- 

 rium. Mr. Gosse did not say much about the difficulties in the way 

 of success, and, in my ignorance, I imagined that marine animals 

 would live in a small receptacle, just as they did in the little rock 

 pools on the shore, not even taking into consideration the fact that 

 these were over-washed twice a day by the tide. I was just ignorant 

 enough to be unaware of my ignorance, and commenced with suffi- 

 cient enthusiasm for a very much greater undertaking, had it only 

 been tempered with a little knowledge or experience. I had a small 

 gold-fish globe, holding perhaps a gallon of water, and this I deemed 

 all sufficient for my purpose, I searched among the rock pools, and 

 brought away one specimen of every different kind of small animal I 

 could find, expecting them all to live and thrive in this little vessel. At 

 least three species of fish, a small "' dog-crab," a hermit crab, a shrimp, 

 a periwinkle, a top shell, a limpet, the latter being on a piece of 

 stone, partly covered with barnacles and small mussels. Some sand 

 and fine gravel was put at the bottom, a few pieces of stone with sea- 

 weeds growing on them were piled up in the centre, and I expected 

 I had done all that was necessary. Within twenty-four hours ever}^- 

 thing was dead, except the limpet. I could not understand it, but 

 was quite ready to try again on the same lines. The dead animals 

 were taken out, the barnacles and mussels scraped off the stone on 

 which the limpet resided, more fish and other things were procured, 

 only to share the fate of their predecessors. I am not sure that I 

 even changed the water. Again it was re-stocked, but I removed 

 the limpet from the stone, which now had a bad smell on the under- 

 side. The sides of the glass were beginning to be coated with green 

 confervso, and on this I placed the limpet. I had some difficulty in 

 getting it to adhere to the double concave glass, which was veiy 

 different from the level but rough surface of the stone on which it 

 had resided. At last it fixed itself, and broAvsed contentedly away, 

 mowing down the confervse in regular curves as it slowly moved 

 along. I do not wish to dwell on my continued failures, nor 

 to record the slow process by which I eventually gained some 

 little idea of the conditions necessary for success. While every- 

 thing else perished, the limpet still survived, and at last I noticed it 



