THE CANADIAN ENTOMOLOGIST. 



carried on should be of some type that is easily covered, for protection of 

 the contents from dust and evaporation, and for the sake of economy 

 should be small. Those known as watch glasses answer well, but deeper 

 glass dishes with separate covers are preferable. The potash mixture may 

 be had at any drug store, the absolute alcohol, clearing fluid, and balsam, 

 as well as the dishes, may be purchased from any good supply house for 

 microscopical materials. Slides and cover-glasses for the mounts are to 

 be procured at the same places. 



In dissecting beetles, the following sequence has been found con- 

 venient, though it may be varied in some cases. As each part is cut off 

 it should be placed at once in a dish of clean water. 



i. Take off the legs, being careful not to destroy the coxa if it is 

 desired to include that joint in the mount. 



2. Remove the elytra and hind wings if they are wanted, otherwise 

 they may be left on the specimen, unless abdominal dissections are 

 required. 



3. If the spiracles are to be examined, take the scissors and separate 

 the lower part of the abdomen from the upper, cutting along just below 

 the sharp lateral edge. As a rule the spiracles are found in the upper 

 portion, the lower may usually be discarded. 



4. Cut off the head. Remove the antennae carefully by digging them 

 out of the cavities in such a way as not to injure the basal joints. Take 

 off the mandibles by forcing each one outward with the point of a heavy 

 pin until it comes loose at the articulation. Now split the head by forcing 

 the tip of the scalpel (which should be long and slender) into the posterior 

 foramen or neck, opening and cutting through one side against the soft 

 wooden block, afterwards turning the instrument over and cutting through 

 the other side. This will separate the top of the head from the lower half. 

 Remove the labrum from the upper half. From the lower the maxillae 

 may now easily be dissected, since their bases are exposed from above, and 

 the labium may be trimmed loose from the remaining tissues. Frequently 

 the mentum is so thick that it is better to study it with a hand lens and 

 to be content with detaching the ligula and palpi for the microscope. 



Throughout the process of dissection care must be taken not to allow 

 the specimen to dry, or it will become brittle and permeated with air 

 bubbles. The parts may safely be left in water for a day or two, or they 

 may be started immediately on the processes leading up to the final 

 mounting, the steps being as follows : 



