ANATOMY AND HISTOLOGY OF LIMAX AGRESTIS. 161 
very fine canals, connecting Semper’s organ with the 
outer world. A further examination gave the following 
results :—The lobes of Semper’s organ are masses of 
glandular cells of pear-shape.. These cells are arranged in 
a bouquet-form, the pointed portion of the bouquet directed 
anteriorly. Also the pointed ends of the pear-shaped cells 
lie anteriorly, and the ends of the individual cells are 
continued into long canals of very small diameter, leading 
to a papilla placed immediately above the lips. The canals 
given off from the individual cells do not seem to unite, 
and so every cell has its own canal leading to the exterior. 
The walls of these canals are formed by squamous epithe- 
lium of most flattened and elongated character, with 
rod-like nuclei. 
In regard to the function of the lips and of Semper's 
organ I cannot say much. I do not think that the lips 
have any other sense than the sense of touch ; for the 
epithelium is of too simple a character to allow us to 
consider the lips as olfactory organs. Semper’s organ 
has probably the function of keeping the lips in a moist 
condition, as soft tissues are certainly more able to receive 
slight impressions than dry and rigid ones. 
The pedal gland.—Another organ of rather mysterious 
character is the pedal gland. ‘Rolleston (8) describes the 
macroscopical appearance of this organ in the following 
words: ‘The internal circular coat of the foot is raised 
into two corrugated ridges along the middle line for the 
greater part of the length of the body by the underlying 
mucous gland. This gland has its bilaterally symmetrical 
halves arranged on either side of a single duct, which 
again is underlaid by a large venous sinus, very visible 
in the living animal along the middle line of the foot 
inferiorly.” According to Claus (1), ‘the wall of the pedal 
cland of Limaz and Arion is composed of unicellular 
11-2 
