Norwegian Solenogastres. 15- 
(fig. 4), project far towards the front, the foremost pair, which 
is the longest, to the anterior corners of the pharyngeal cavity. 
Only the foremost project freely, the succeeding ones are lodged 
beneath the preceding teeth and lie close to the wall of the pha- 
ryngeal sac. Towards the posterior ends of the lateral divertic- 
les the teeth diminish in size up to the apex, where the series 
terminates with a spiral coil (cf. fig. 4). 
In the median part of the radula the teeth, on the other 
hand, grow somewhat larger towards the rear end (fig. 1), which 
terminates blindly a short distance behind the oesophagus. Interi- 
orly this part of the radula sac is divided by a vertical septum 
(figs. 4, 10 e.) extending forward to the oesophagus, where it 
disappears. At both sides of this fold, between it and the exter- 
nal wall of the sac, the teeth are secreted in the shape of a 
gelatinous substance (fig. 10) stained with haematoxylin, faintly 
in its interior, stronger at its periphery. The epithelium lining 
the sac medially as well as laterally consists of polyedric cells. 
with rounded nuclei. At the posterior end, the epithelium forms 
a pocket round each tooth; anteriorly, the pockets become indis- 
tinct and the teeth form a continuous band. Towards the front 
the epithelium becomes lower until finally, where the median 
septum disappears (fig. 9), it loses at this side its contact with the 
teeth. Now only the small basal cells remain, lining the lateral 
wall on which the teeth are fixed. The said epithelium partakes 
in the flexion of the anterior region of the radula, and then lines 
the whole inner side of the lateral coecum. 
At the rearmost end of this lateral process the tooth-plates 
originate as vertical stripes of cuticula with a finely serrated free 
edge (fig. 6); the denticulation, however, is obliterated towards 
the front (fig. 5), and only the strong dorsal spine is developed. 
Traces of the primary denticulation may however appear in the 
sides of the largest anterior teeth. The epithelium from which 
the teeth proceed is of the same kind as in the median part; also 
in the lateral diverticles its elements are more distinct at the rear 
end than anteriorly. 
Close in front of the radula two small lateral pockets appear 
separating the latter from the pharyngeal cavity (fig. 4). In the 
latter portion the epithelium is thicker and consists of cylindric 
cells producing a very thick and soft cuticula, which covers the 
tooth spines, at least laterally, but seems to be different from the 
tooth substance and does not fuse with it. 
