7400 Fishes. 



Eggs, 5, 6. Gray, with red-brown spots, but frequently white and 



unspotted. 



, Edward Newman. 



(To be continued). 



Fish Devoured by Snails : Longevity of the Sticklcbach.—The freshwater aquarium 

 is now so commou an object of attention that probably few of the many interesting 

 facts to be observed in the habits of its inmates remain unrecorded. I was not, how- 

 ever, fnlly aware until rather lately that the larger water snails (Limneus pereger at 

 least) catch and devour the small fish when they are placed with them in confinement, 

 but whether this is the case in their native pools and streams I am not able to say. I 

 was for some time at a loss to discover what could occasion the death of several min- 

 nows which I found mutilated and partly eaten, when at length I perceived one 

 apparently just caught, with its tail in the grasp of a large Limneus. This, I think, 

 happened repeatedly, and served lo acquit of the destruction a fine silver fish, which 

 I had been ready lo accuse in this matter. I never witnessed the actual capture, and 

 am still puzzled to imagine how such agile little creatures, darting rapidly here and 

 there amongst the aquatic foliage, can fall a prey to the slow-paced mollusks which 

 cling to the glass or the rock, or glide with scarcely perceptible molion, shell down- 

 wards, on the surface of the water. That elegant and curious insect called (I believe, 

 hut am not learned in these matters) the " water-boatman" (Notonecta), soon had to 

 be dismissed, much as I enjoyed watching his evolutions ; he clearly made too great 

 havoc among his finny companions ; but there was no mystery in this, considering the 

 swiftness of his movements. The Paludina vivipara, though here of a very large size, 

 seems perfectly harmless, and, as far as can be seen, eats neither animal nor plant in a 

 living stale, subsisting on the decaying vegetation, or perhaps on the Infusoria and 

 other creatures invisible to the naked eye. Of these latter, the litile " world of water " 

 in the aquarium seems to contain an endless and most beautiful variety, affording a 

 vast supply of wonders for the microscope ; indeed a common pocket lens will often 

 reveal a fringe of animated flowers, or wine-glass-shaped animals, adhering to the 

 leaves of the Chara and other water plants. The Paludina, Bythinia, &c., bury them- 

 selves for weeks or months in the soil at the bottom, and crawl up at intervals, their 

 shells sometimes clothed with a branching moss-like vegetation. The larger specimens 

 of Limneus pereger seemed all to die last summer, as soon as the eggs were laid, but 

 the smaller ones have continued alive and still growing for a long time. When they 

 die the animal often remains attached to a plant or other substance while the shell 

 becomes loosened and drops off, perfectly empty to the tip of the spire. This accounts 

 for what had often excited my surprise when collecting for a cabinet, viz., the large 

 number of fresh and clean specimens to be found amongst the drift from the river in 

 time of flood, showing that the mollusk had not decayed away in its covering as one 

 might expect. The eggs are worth examining in the tnicroscope, the movements of 

 the little snails being very discernible through the transparent membrane enclosing 

 them. Yarrell says the stickleback lives only about two years; one of mine has been 

 in the aquarium, I think, nearly double that time, and continues an exceedingly tame 

 and amusing pet, always couiing to my fingers to be fed or noticed when anything 

 requires attention in its neighbourhood. — K.; Sudbury, January 10, 1861. 



