SEA-FISHERIES LABORATORY. 321 



the posterior end are the retractor muscles of the pro- 

 stomium and nuchal organ. x TO. 



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- 

 fibrillae (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 oesophageal 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 

 otocyst of a specimen 250 mm. 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. 



Y 



