10 JOURNAL OF THE [January, 



attack the thin membrane, upon which are situated the lingual 

 teeth, and which holds them in position. 



After removal from the burner, water is added and the undis- 

 solved material allowed to precipitate. With a pipette having a 

 rubber bulb, or by decanting, the fluid is nearly all removed, 

 and clean water again added. This is repeated, until the 

 potash and light flocculent matter are eliminated. 



The residue is then washed into a flat-bottomed dish, or large 

 watch crystal, and the radulee, in the majority of cases, can be 

 perceived by the unassisted eye, and removed, by means of fine, 

 mounted needles, to another receptacle containing a very small 

 amount of water. In case the radulse are very small, the mate- 

 rial is transferred drop by drop, with a pipette, and examined, 

 under a one inch or three-quarter inch objective, on the hori- 

 zontal stage of a microscope, preferably furnished with an 

 erector. They can then be removed from the mass of extra- 

 neous matter, and placed in a separate receptacle, as in the 

 former instance. 



A drop of strong chromic acid is added to the specimens, and 

 in from one to two minutes the teeth on the radulae are stained 

 a light yellow or amber colox. After washing out the chromic 

 acid, the specimens are dehydrated in the usual way, and after 

 removing the acohol with a pipette, absorbent paper, and partial 

 evaporation, oil of cloves is added, and the specimens are ready 

 for mounting in Canada balsam. 



The lingual membranes will be found to be more or less 

 coiled, and usually attached to the jaws. It is desirable, in the 

 mounted specimen, to have the membrane flattened out, with the 

 dentiferous side uppermost, and dissociated from the jaw. 

 Some species have a large strong jaw, which, if left with the 

 lingual membrane, will raise the cover glass so far above the 

 denticles as to exclude the use of the higher powers of the 

 microscope. Therefore, some mechanical work is necessary to 

 unfold the radula, and remove the jaw. Having provided a 

 clean glass slide on the turn-table, the specimen is taken from 

 the clove oil and centered on the slide. Now placed under the 

 microscope provided with an erector, and using mounted needles, 

 the radula is easily unrolled with the dentiferous side upper- 

 most and the jaw removed. Replaced upon the turn-table, a 

 thin cover-glass is superimposed and centered. The cover- 



