60 CHAETUDEllMA ERUUITA. 



columnar cells of greater height than those of the adjoining epithelium. In one 

 specimen -killed in vom Rath's fluid the protoplasm of the comjionent cells is 

 much vacuolated or in a very small number contains a granular secretion. Poste- 

 rior to the radula, whose general appearance is sufficiently shown (folate 29, 

 fig. S), the pharynx becomes dorso-ventrally compressed, then circular and 

 opens into the stomach. This is a relatively spacious organ with tliin unfolded 

 walls that posteriorly become thicker and folded. The relation of intestine and 

 liver are typical and require no description. In the proximal part of the liver, and 

 throughout the major portion of the intestine, there are considerable quantities 

 of organic remains, diatoms, sponge spicules, a few fragments of entomostra- 

 cans, and several chambered Foraminifera whose protoplasm was only partially 

 digested. 



The nervous system of this species is exceptionally clearly tlehnetl in one 

 specimen killed in vom Rath's fluid and for this reason has been more thoroughly 

 studietl than any other species of the genus described in the present jiaper with 

 the exception of C. (tttvnudld. The brain is very distinctly bilobed, a deep 

 indentation occurring on its anterior surface. From its lateral and forward 

 borders nerves pass into the ])recerebral ganglia which in tiu'ii send tremendous 

 bundles of fibres to the Iniccal sensory plate. In some sjiecies the connectives 

 to the pedal, lateral, and labio-buccal systems have distinct origins in the brain, 

 l)ut in the present case they are united for a considerable tlistance (Plate 13, 

 fig. 3). Each of these compound coimectives after leaving the brain and pass- 

 ing forward a short distance gives rise to the labio-buccal connective and con- 

 siderably farther on the pedal anil lateral connectives lieconie differentiated. 

 The pedal and lateral ganglia are in \\w usual positions and are unit(>d l)v 

 freciuent connectives and connnissures. At the points of origin of thes(> nerves 

 there are no very cleai'ly dehned enlargements though anteriorly the pedal 

 and lateral cords are of large size and gradually taper posteriorly, attaining 

 their average size about the hinder border of the prothoi'ax. As these ganglia 

 diminish in size the connectives and commissures become reduced in calibre and 

 are difficult to follow yet they may be traced here and there throughout the 

 entire length of the animal. 



As in C. aUenuala a nerve arises from each lahio-ljuccal connective 

 about the level of the forward border of the radula and ])a,ssing inward and 

 downward joins a small subradular ganglionic mass. In this sjiecies the gan- 

 glion shows no indication of being paired. Each of these subradular connectives 

 gives rise to a ner\e distributed to the subratluiar organ and more laterally swells 



