178 lUMlU-ES BY III VERS. 



form a principal portion of the food of many savage nations, and are eaten 

 by civilized ones as great delicacies, and our Government Botanist, in one 

 of his explorations, having lost his way, subsisted for several days on a 

 species of mussel. Their structure, too, is wonderful. The specimens which 

 we procure here more commonly are animals belonging to the Gasteropoda, 

 or air-breathing shell, and are without an operculum, or covering to their 

 habitation; this flat, many-whorled shell, somewhat like that of a Nautilus, 

 is a Planorbis, and great care must be taken in handling it, being brittle 

 and easily broken. The next, which is ovate, also very thin, with a large 

 aperture, is a Pliysa, so named from its pouch-like appearance, and both 

 genera are widely distributed throughout the world. Now watch them, how 

 industriously they are cleaning off the film or conferva which has commenced 

 growing on the sides of the bottle; you will observe, too, with a small 

 pocket lens, how the tongue is used, — the upper lip with its mandible is 

 raised, the lower lip, which is shaped like a horse-shoe, expands, the tongue 

 is protruded and applied to the surface for an instant, and then withdrawn; 

 its teeth glitter like glass-paper, and in Lymnea, an allied genus, which is 

 also here, it is so flexible, that frequently it will catch against projecting 

 points, and be drawn out of shape slightly as it vibrates over the surface. 

 The large shell which you observe so frequently on the bank, and the 

 trees which lie half in half out of the water, is a Unio; and from the 

 manner in which one end is invariably broken, it is evidently brought 

 there by some water animal which preys on its flesh — probably the water- 

 rat. Truly, much as we admire well-kept Botanic Gardens, there is 

 nothing which so thoroughly refreshes us as a ramble away from the 

 conventionalities of town life, where we can breathe freely without fear 

 of criticism; and we are inclined to think too with Headley, an agreeable 

 writer, whose "Life in the Woods" we lately met with, that one degen- 

 erates without frequent communion with nature. "A single tree," says 

 he, "standing alone, and waving all day long its green crown in the 

 summer wind, is to me more full of meaning and instruction than the crowded 

 mart or the gorgeously built town." Many is the happy hour we have ere now 

 whiled away by the river side, after all our artifices had failed to lure the 

 fiuny tribe into our creel, half dreamy quiet thoughts stealing over us as the 

 stream rolled onwards, from which we were roused only by the remem- 

 brance that we had many weary miles to trudge before we could reach 

 our destination. Happy days, indeed, on which we look back with pleasure, 

 not unmingled with sadness, — for whose dreams are ever realized? 



But to the scum which covers the surface of the water. What use 

 is that? Ah! peep through a microscope at a small portion, and tell us 

 what you see there: hair-like filaments of the most exquisite patterns art 

 could produce — long tubular cells containing beautiful green spiral coils, 



