12 LAND AND FRESH-WATER SHELLS. 



along the under surface of the foot in the middle line ; the place 

 which the viscera held is stuffed with wadding, and the skin is 

 dried and varnished. In the other recommended by Dubreuil 

 the slug is killed and washed in pure water, to which, after the 

 lapse of eight hours, some salt is added. A slit is then made 

 along the left side, and the animal skinned. Thus, by means of 

 two more longitudinal slits, three preparations can be made one 

 to show the back, one the foot, and the third the right side with 

 the pulmonary orifice. These are glued on cardboard, varnished 

 with white shellac varnish, to which a little corrosive sublimate 

 has been added, and duly labelled.* 



The wet method is simply their immersion in some one fluid 

 preservative medium. This may be turpentine, equal parts of 

 glycerine and methylated spirit, or preferably one of the following 

 fluids, which can be made with slight trouble. 



(i). Wickerheimer* s Fluid. 

 Dissolve in 3,000 grammes of boiling water 

 TOD alum, 



25 common salt, 



12 saltpetre, 



60 carbonate of potash, 



10 arsenious acid. 



This solution is to be cooled and filtered, and to every ten litres 

 of it four litres of glycerine and one litre of methylated spirit are 

 to be added. 



(2). Poetz and Hohrs Fluid. 

 Arsenious acid ... ... ... ... 12 grammes 



Sodium chloride ... ... ... 60 ,, 



Potassium sulphite 150 



nitrate 18 



carbonate 15 



Water ... ... ... ... ... 10 litres 



Glycerine 4 



Wood-naphtha ... ... ... ... f ,, 



* There is a separate method for the preservation of Testacella. The animai 

 is dried in sand, then slit along its under surface, stuffed with cotton wool 

 and redf ; ~1 



