JOURNAL OF ENTOMOLOGY AND ZOOLOGY 139 
Tore Animentary Canau. The mouth opens on the ventral 
side, as a large, laminated opening covered with ciliated epithe- 
lium, which leads into a cavity in which the end of the buccal 
mass projects. This buccal mass consists of two layers of muscle 
with a food chamber between. The outer layer consists of a 
heavy mass of circularly disposed fibres, opening anteriorly into 
the mouth cavity by means of a narrow slit. This outer mass 
is covered by a regularly ridged cuticle, secreted by a layer of 
short, columnar cells, which is especially heavy near the free end 
and becomes thin and flat near the base of the buccal mass. 
Within these circular muscles is a cavity into which projects 
the muscles over which the radula moves. These consist of two 
lateral masses, fastened together below by a band of muscle, and 
above by a thin layer which consists mainly of epithelium. Be- 
tween these two masses is a cavity, which communicates directly 
with the arterial system. The radula is grooved above this 
cavity so as to dip down into it. Toward the posterior end of 
the buccal mass sinuses appear between the outer muscles and 
the epithelium lining the buccal cavity and extend in size, as 
the buccal food cavity diminishes, so that the posterior part of 
the muscles of the radula is almost entirely surrounded by 
sinuses. When this takes place the sinus between the radula 
muscles communicates with those surrounding them. At the 
posterior end of the buccal mass the different sets of muscles 
gradually blend together. The gland where the formation of 
the radula takes place is situated in the continuation of the 
groove between the muscles over which the radula moves. It 
is situated at the extreme end of the buccal mass where it pro- 
jects as a little knob. It is lined with tall slender columnar cells, 
with a dark-staining granular protoplasm and oval nuclei situ- 
ated near the center of the cell. At the upper side of the capsule 
is a mass of undifferentiated tissue from which several layers 
of large irregular shaped cells branch off. In the space between 
these two kinds of cells the radula is formed, the teeth probably 
by the irregular inner cells and the basement membrane by the 
columnar lining layer. From the mouth the food passes through 
the cavity between the two sets of muscles, and up over the 
