VIII. INSTRUCTIONS FOR COLLECTING AND PREPARING 



LYMN^AS. 



COLLECTING. Lymnseas may be collected in bottles, cans, or almost 

 any receptacle. A wire scoop attached to a long handle is a good 

 utensil to use in picking up floating individuals or for scooping up those 

 species inhabiting the deeper water. 



PREPARATION FOR DRY STUDY. The shell may be prepared by 

 placing the animal in boiling water, which kills it, after which the soft 

 parts are easily withdrawn with a pin or needle. The shell may then 

 be washed and dried and is ready for the cabinet. In case the shell 

 is encrusted with lime or some other matter, a judicious use of oxalic 

 acid may be necessary to clean it well. 



PREPARATION FOR ANATOMICAL STUDY. Lymnseas may be killed 

 by placing them in boiling water, after which they may be preserved 

 in 60% alcohol. They should never be placed directly in alcohol, as 

 this causes too much contraction for subsequent work. Should these 

 facilities not be available, it is permissible to preserve specimens in 

 alcohol, as any kind of a specimen is better than none, especially in 

 the case of those species which live in little frequented parts of the 

 country. Plunging in alcohol does not affect the Lymnaeas as much 

 as it does the land shells. On no account use formolyn (formalde- 

 hyde), as this medium makes the animal brittle, besides ruining the 

 eyesight of the one studying the material. 



DISSECTING. The dissecting of Lymnseas is not difficult. All that 

 is necessary is a dissecting microscope, a shallow pan with a cork or 

 wax bottom into which pins may be stuck, a pair of fine-pointed scissors 

 and plenty of fine-pointed pins (insect pins are the best). If care be 

 observed, the genitalia, the digestive system, the central nerve mass 

 and the respiratory and renal organs may be spread out and easily 

 studied. (See plate 1.) The animal, after removal from its shell, 

 may be opened by making an incision from the top of the back to the 

 upper coils of the body and the flaps of the cut mantle turned aside 

 and pinned to the bottom of the tray. In this position, with the head 

 toward the observer, the genitalia will be seen to the left, the buccal 

 sac and general digestive tract in the center, and the respiratory cavity 

 and renal organ to the right. If the incision be made to the left of 



