200 CHAETODERMA LUCIDUM. 



The sense cells are exceedingly long and slender with spindle-shaped nuclei, 

 and internally may be followed into the vicinity of the great nerve bundles 

 passing from the brain into the region of the buccal sensory plate. 



Gland cells, attached to the great ganglionic masses applied to the brain 

 or scattered irregularly anterior to the mouth opening, communicate with 

 clearly defined ductules leading to the margins of the buccal plate. Even in 

 moderately stained (Delafield's haematoxyUn) material these cells are almost 

 black while the ductules are purple. 



The mouth, whose position has been described in a foregoing paragraph, 

 communicates with a canal of moderate size in which the elements, muscular 

 and epithelial, present the customary appearance. Buccal or pharyngeal 

 glands are present in an unusually restricted area. On each side of the mid 

 line a very short distance posterior to the brain they appear as a single lobule 

 (Plate 9, fig. 13) or as two or three closely appressed lobules in which the cells 

 are unusually compact owing to an abundance of a finely granular, moderately 

 staining secretion. 



A median ventral ridge immediately anterior to the radula probably repre- 

 sents the subradular organ of other species. The cells are not so distinctly 

 columnar as in Chaetoderma attenuata for example, and consequently are not 

 sharply differentiated from the adjoining cells. Nevertheless the absence 

 of folds in the ridge and the fact that it rests upon a typical ganglion with con- 

 nectives marks it as a definite sense organ. 



In several species where the subradular organ and the related nerve supply 

 have been well preserved a lobule of gland cells attaches to the ventral side 

 of the digestive tract on each side of the subradular ganghon. This happens 

 so invariably that it furnishes some evidence for the belief that these organs 

 correspond to the ventral salivary glands in the neomenians, while the scattered 

 yet compact glands attached to the dorsal or even lateral surface represent 

 the dorsal salivary glands. There is at present no more cogent reason than 

 their position for such an opinion, but their constancy indicates that they are 

 structures of long standing. 



The radula and its supports and musculature are relatively heavy (Plate 10, 

 fig. 1) but otherwise typical. 



Posterior to the radula the alimentary canal narrows rapidly and unites 

 with a highly enlarged section with very thin walls. The outer or proximal 

 boimdaries of the lining cells are clearly defined, but the presence of large quan- 

 tities of a granular secretion in the neighboring lumen suggests that in the act 

 of bringing the animal to the surface or owing to the method of fixation the 



