130 LOPHOMENIA SPIRALIS. 



are fairly well filled with small particles which in the larger cells are applied to 

 the cell membrane, the remaining contents consisting apparently in life of a 

 fluid. In the majority of cases the nucleus is spherical, finely granular and 

 contains a distinct nucleolus. 



The position of the radula is shown in Plate 6, fig. 5, while a cross section 

 of the radula tube is represented (Plate 34, fig. 1). From these it will be seen 

 that this organ belongs to the distichous type and that there are about twenty 

 rows of teeth. While the shape of each tooth is sufficiently shown in the figures 

 it is worthy of note that in the radula tube the base of each tooth is connected 

 by a narrow cuticular bridge. When the radula opens out into the pharynx 

 each plate appears to split in half, at all events the exposed teeth in one specimen 

 at least are fully three times farther apart than in the radula tube and they do 

 not appear to be connected by a basal plate. 



Immediately in front of the radula there is a pair of short diverticula of the 

 pharyngeal wall which serve as outlets of the salivary secretion. The mass of 

 the outlying gland comprises several divisions bounded by connective tissue 

 and located chiefly at the sides of the pharynx. The cells themselves are pyri- 

 form, highly vacuolated and their ductules attach chiefly to the dorsal side of 

 the main duct. 



The stomach-intestine assumes its average diameter at once and gut pouches 

 appear close to the anterior end. No forward coecum is present. The epithelial 

 cells lining the tract at first form a flat surface but a short distance backward 

 they become arranged in the form of longitudinal folds (Plate 19, fig. 3) that 

 continue to the neighborhood of the accessory reproductive organs. In the 

 latter region the diameter of the intestine decreases, its lining walls are smooth, 

 and wedged in between the cloacal passage and the pericardium, it makes its 

 way to the cloaca. The cells of the rectum are pear shaped with basally situated 

 dense nuclei and the distal portions are swollen with a secretion that in the form 

 of a darkly staining finely granular mass fills the lumen of the gut. 



In this species the pericardium is long and the contained heart is relatively 

 slender (Plate 8, fig. 0). The blood from the posterior part of the body enters 

 the hinder extremity of the heart which here has the form of a very slender tube 

 (Plate 19, fig. 9), attached to the dorsal wall of the pericardium. About midway 

 in the pericardial cavity this canal enters another section, of four or five times 

 greater diameter, that for a short distance hangs freely in the pericardium but 

 more anteriorly unites with the pericardial wall and with gradually diminishing 

 calibre holds this relation until it passes into the aorta. This latter vessel 



