112 THE SNAIL. 



Clean the anal opening and groove, and pass a seeker into 

 the anus and back along the rectum. 



V. The aperture of the pedal mucous gland is 

 immediately below the inferior lip, between 

 the head and the foot. 

 Pass a seeker into the aperture, and backtvards along the 

 gland, and lay the gland open along its whole length. 



B. After Removal of the Shell. 



Twist the animal out of the shell, taking care not to 

 damage the upper part of the body in so doing. The shell 

 comes off readily if the snail has been put in spirit for a short 

 time after drowning. 



1. The Shell. 



a. The colour differs a good deal in different specimens. 



The ground colour is a yellowish brown, marked 

 by darker longitudinal bands running round the 

 spiral, and by obliquely transverse lines corre- 

 sponding to the lines of growth. 



b. The nucleus is the oldest part of the shell, at the top 



of the spiral, corresponding to the umbo of the 

 mussel-shell. 



c. The mouth is oval, and notched posteriorly by the 



penultimate turn of the shell. Its lip is smooth 

 and slightly everted. 



d. The lines of growth are transverse ridges parallel 



to the mouth, and indicating successive positions 

 of the mouth during the growth of the shell. 



e. The umbilicus is an opening on the under surface 



of the shell leading into the hollow axis or 

 columella. It is sometimes closed. 



Clip aioay one half of the shell ivith bone forceps, and 

 grind the cut edges flat on a file or stone. 



f. The columella is the axial portion of the shell 



round which it is coiled ; it is formed by the inner 



