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the posterior end are the retractor muscles of the pro- 
stomium and nuchal organ. x 70. 
Fig. 48. Part of a similar section showing an eye 
imbedded in the brain. In the upper part cuticle and 
prostomial epithelium are shown, on the right a gland 
cell and on the left a bundle of slender sense cells. 
Beneath the epithelium is the anterior brain lobe and an 
eye, which consists of a cup-shaped mass of reddish-brown 
pigment spherules grasping a spherical lens. In the 
right of the pigment mass is a nucleus and small amount 
of protoplasm, probably the remains of the cell in which 
the eye has been formed. x 550. 
Fig. 49. Section of otocyst and tube leading to ex- 
terior (from specimen 60 mm. long). The otocyst is 
lined by epithelium continuous with that of the tube and 
the epidermis. In the outer portions of the tube there 
are fusiform sense cells, but in the otocyst itself the sense 
cells are distinguished only by the presence of neuro- 
fibrille (not shown in the figure). The proximal (and 
narrowest) portion of the tube is ciliated. Below the 
epithelium of the otocyst is the nerve sheath, connected 
with the stout nerve from the esophageal connective. 
This nerve, along the course of which are numerous ganglion 
cells, also sends off branches to the skin. The otoliths are 
irregular bodies, chiefly quartz grains. x 210. 
Fig. 50. Camera-drawing of the cuticle lining the 
otoeyst of a specimen 250 min. long. This is thicker than 
in younger specimens. ‘The tube is almost blocked and the 
otoliths are now assuming a rounded outline, due to the 
deposition of layers of secretion. x 210. 
Fig. 51. A small portion of epithelium from anterior 
end of stomach, showing two large goblet cells. The 
secretion of these cells has been coagulated on preservation 
and now appears as a reticulum, x 210. 
R 
