51 
carrying the teeth is seereted by the underlying epithelium , where- 
as the teeth themselves are secreted and deposited upon this 
common basis by the epithelium opposite. The radula is continued 
backwards and makes one turn upon itself (fig. 20, RE’). In the 
hinder portions it appears folded, the lumen in which it is enclosed 
beeoming considerably restrieted. Its greatest breadth is 0.25 mm. 
Tongue cartilages are not present; still in the base of the ton- 
gue lateral enlarged cells with small nuclei make their appearance 
in the midst of the muscular tissue. In some places they are 
somewhat accum:ılated and might perhaps well be regarded as a 
more indifferent or primitive stage of such cartilaginous tissue. 
Moreover the base of the tongue is anteriorly pierced by two canals 
(fig. 21, s and s‘) which unite and then communicate, as does the 
radular sac itself, with the short canal, opening out into the pha- 
rynx by the slitr. After their bifurcation these two branches still 
retain for a very short distance their pharyngeal epithelium (fig. 
21), then they suddenly change this for a glandular epithelium ofa 
distinet character and we find ourselves amongst long ceylindrical ducts, 
oecupying about one fourth of the length of the animal (they mea- 
sure 25 mm. in the specimen of 105 mm.) and ending blindly. 
These ducts are parallel to each other and to the body axis and 
3 mm. apart (fig. 16). They are generally covered from view by the 
folds of the intestine (fig. 14 and 23) and only visible when these are 
removed (fig. 15). The lumen, which in spirit specimens is always 
more or less triangular (fig. 23) is here and there filled by a se- 
eretion; and 1 do not hesitate in looking upon these organs as 
salivary glands. | 
The cells constituting the glandular epithelium are elongated and 
superposed in a multiple layer. ‘Their contents are more or less 
coarsely granular (fig. 23, s) and the strongly stained nuclei stand 
out very clearly. I could find no trace of ciliation. The secretion 
(after preservation in spirit) is very finely granular and appears to 
stain diffieultiy with pierocarmine. The external wall of the gland 
is muscular, a layer of circular fibres being situated internally 
with a certain number of longitudinal bundles externally. The 
