THE GARDEN SLUG. 65 
camel-hair brush, and examine with the inch ob- 
jective. Cover with a slip of thin glass, and flatten 
it out by gently pressing down the glass with the 
handle of a needle. Notice on each of the pedal 
ganglia a more or less round, dark greyish spot. 
These are the auditory sacs. Examined with the 
quarter objective, they will be found to contain a 
large number of calcareous ofoliths. Examine the 
nervous tissue of the ganglia and cords. Cut off 
the tip of an eye-peduncle, and examine the eye. 
There are four different species of garden slugs. The 
foregoing description applies to Limax molestus, The 
anatomy of the others differs in some respects, especially 
in the details of the reproductive system. The following 
analysis will enable the student to ascertain the name of the 
species he is examining :— 
Reproductive opening behind the base of the right tentacle; no 
gland on the tail. 
Back not keeled up to the mantle—Limaz molestus. 
Back keeled up to the mantle. 
Mantle rounded behind—Jiilax antipodum. 
Mantle emarginate behind—Wilax emarginatus. 
Reproductive opening below the pulmonary opening ; a gland on the 
upper side of the extremity of the tail. 
Dark lead-grey, with a yellow foot— Avion incommodus, 
