I04 



HARDWICKE'S SCIENCE-GOSSIP. 



Although staying in the district indicated from 

 early in May until the close of the third week in 

 August, I never saw but two nests of the humble- 

 bees, and both these were nests of the moss or 

 carder ; though continually on the look-out for any- 

 thing pertaining to insect life, and having the co- 

 operation of several active and intelligent youngsters 

 keen to tell, show, or bring me things pertaining to 

 Natural History. One evening, on returning from 

 a walk, I was greeted with the information of a 

 " Meggy-mony-feet " of two colours, having been 

 found beneath some loose soil and stones near an 

 outhouse, and which had been preserved for me. 

 Though knowing that a " Meggy-mony {i.e. many) 

 feet " meant a centipede of some description, I was 

 rather dubious as to what I should find in the box 

 into which the captive had been put, since a centipede 

 of two distinct colours I was unacquainted with. 

 However, on raising the lid of the receptacle, there 

 truly was a fine centipede (a species of Lithobius, if 

 I err not) of two very distinct colours, being in the 

 anterior two-thirds of its length of a light lead-grey 

 colour, while in its posterior one-third it was of the 

 normal yellow-brown ; this strange disposition of 

 colours being due to the fact of this myriapod being 

 in the act of casting its skin or shell, which was 

 being passed backwards along the body, and the new 

 soft integuments beneath having not yet attained 



their normal hue. 



Charles Roeson, 



Elswick, Newcastle-tipon-Tyne. 



WATER-SNAILS ; A STUDY OF POND LIFE. 

 By the Author of "Plant Life." 



[Coniinued/rom fage 8i.] 



WE have seen all we can of its external appear- 

 ance, now let us take a glance at its interior. 

 We take a specimen of the large pond-snail {LimiKza 

 stagnalis), and dip it into boili7tg^a.iQX. Death is in- 

 stantaneous, and consequently painless. Now place it 

 in cold water for a few minutes, insert a pin or needle 

 into the animal and so extract it from the shell. Now 

 pin it out on a piece of flat cork or wood, or what is 

 better get a shallow wooden trough, a few inches square 

 and an inch and a half deep, and pin the snail to the 

 bottom. In doing this be sure that the pins pass 

 through the skin, or "mantle," only. Now cover 

 the specimen with water, and with a fine pair of 

 scissors cut through the mantle from the head to 

 the small end. This will necessitate an alteration 

 in the pins, so as to lay open the interior. We have 

 now the principal organs exposed, and, commencing 

 from the head, the most striking is the " buccal-mass," 

 a cluster of muscles enclosing the mouth. By care- 

 fully cutting through this mass we may extract the 

 "lingual membrane." 

 Just below the buccal-mass we notice a number of 



fine white branching threads given off on each side. 

 These are the "ganglia" of the nervous system, and 

 by carefully clearing away the salivary glands we 

 may trace these ganglia for some distance. One set 

 distributes its branches over the region of the head, and 

 is hence called the cerebral ganglia ; others transmit 

 sensation from the " foot " {pedal ganglia), whilst a 

 third set gives sensitiveness to the mantle and the 

 stomach {parielo-splancknic). These ganglia consti- 

 tute the whole nervous system of the animal, and 

 their thickest portions form a ring round the oeso- 

 phagus. This oesophagus is continued backwards to 

 the stomach from which it passes as the intestine, 

 which returns nearly to the head, and has its external 

 aperture beneath the fold of the mantle. The smaller 



Fig. 72. — Successive stages in the development of 

 L im ntea j>ereger. 



end of the animal is seen to consist of a large brown 

 granular mass surrounding the stomach and through 

 which the intestine winds. This mass is the liver. 

 Previous to the intestine entering the substance of 

 the liver it enlarges considerably, the enlarged portion 

 constituting the gizzard. Near it are the salivaiy 

 glands, long, yellow fatty masses, and the renal organ 

 and mucous gland. The renal organ is analogous 

 to the kidney in higher animals, and the mucous 

 gland supplies the copious discharge of slimy matter 

 by means of which these creatures ghde over various 

 surfaces. The intestine, it should be noted, after 

 taking its course through and around the liver, returns 

 towards the snail's head and seeks the surface on the 

 right side just beneath the fold of the "mantle," or 

 outer skin. In the same region is the opening of the 



