138 OUR FRKSH- WATER MOLLUSCA. 



You have, in all probability, read descriptions of the tide-pools left among 

 the rocks on the Devonshire coast. The accounts in Gesso's "Rambles," 

 or Kingsley's "Glaucus," make you wonder how you have contrived to live 

 so long by the sea-side without discovering all or any of these marvels of 

 Nature; or, if you live inland, have inspired you with a vehement desire 

 to proceed, without more delay, to the coast. If you do so, and follow 

 the recommendations of the two good and talented authors I have named, 

 you will gain a somewhat better and more substantial enjoyment than is 

 generally to be picked up among the idle frivolities of a fashionable 

 **watering-place." 



But if relentless fate shuts you out, as it does me, from the blue ocean, 

 the nearest ditch in your neighbourhood will afiFord a not unapt analogy 

 to the tide-pools^ for which you sigh, and furnish you with an ample field 

 for wonder and reflection. Let us take a look into this one, and in any 

 of the midland or southern counties of England, however flat or uninter- 

 esting they may be, you will have no difl5culty in realizing my imperfect 

 picture. 



It is a still, bright day, early in June, and as you peer downwards 

 into the deep, quiet water, you will again observe with wonder how every- 

 thing in Nature teems with life and enjoyment. At the bottom of the 

 transparent water the long filamentous leaves of Jlottonia palustris present 

 an apt comparison to the thread-like algas of your Devonshire rock-pool, 

 save that they have already raised above the surface their spikes of delicate 

 pink flowers. You will see a good carpeting of MyriophyUum !>picatum — 

 another filamentous, though less conspicuous plant; and, possibly, that 

 mysterious intruder, Anachoris alsinastrum has already insinuated its soft 

 green masses into your pool. In the more shallow water the rigid forms 

 of Hippuris vulgaris and Iris pseudacorus will probably appear, and some 

 of the deeper water be shaded with the broad leaves of the water-lily. 

 And now for the inhabitants — their name is legion — of this bright and 

 variegated forest. Those large beetles, "sculling" about among the Ilottonia 

 leaves, are the Hydropiceus—ihe largest of our aquatic Coleoptcra. On 

 the soft mud at the bottom a couple of water-newts, or "efts," are lazily 

 travelling, and seem to wonder at the vagaries of half a dozen large "horse- 

 leeches," which are meandering about in full enjoyment of life and liberty. 

 The submerged stalks of the aquatic plants are covered with the young 

 of a hundred varieties of gnat and water-fly, from the delicately-formed 

 young of the Tipulcs, to the great locust-like larva of the LiheJlulce. But 

 turn from these wonders to the Mollusca, for it is these that I now want 

 you to notice. 



Floating on the surface, and looking as if they were walking on an in- 

 verted pane of glass, are four or five species of Planorhis. P. corneus is 



