30 NILS HJ. ODHNER, STUDIES ON RECENT CHAMIDAE. 



The nervous system (tig. 27). From the cerebral ganglia, which are situated 

 close above the labial palps surrounded on their posterior and exteriör sides by con- 

 nective tissue, there emerges on the dorsal side, with an anterior direction, a nerve 

 to the under side of the adductor, and closely behind it there appears, on the right 

 side, a smaller one that had no correspondance on the left side. On the antero- 

 inferior side of the ganglia and slightly separated from them a small buccal centre 

 exists (ef. fig. 23), from which a nerve descends into the posterior palp and from 

 which the inferior pharyngeal commissure emerges. This fact implies an agreement 

 with Gh. pellucida, but the present form does not exhibit so perfect a separation of 

 the buccal ganglia from the cerebral centra as is presented by the latter species. 



From the posterior side of the cerebral ganglia there emerge the pedal and 

 the visceral connectives and on their inner side the dorsal pharyngeal commissure 

 and the dorsal pallial nerves. The path of the latter is of interest. The left one 

 soon plunges through the body wall, penetrates the liver and approaches the oeso- 

 phagus on its upper and frontal side, and finally reaches the epithelium. The right 

 one is considerably weaker, runs superficially near the frontal branchial margin and 

 disappears in the median line on a lower level than the left one. 



In Chama pellucida, too, which is attached by its left side, there occurs a 

 stronger left and weaker right pallial nerve (Grieser 1913). 



The cerebro-visceral connectives penetrate the liver and run about halfway be- 

 tween the stomach and the surface of body. Just in front of the pericard there 

 exists a sort of commissure between them, composed, just as in Ch. pellucida, of 

 some branches which innervate the genital organs and the nephridia. 



From the visceral ganglion, which is considerably larger than the cerebral ones, 

 two pairs of nerves start on the back side, the stronger ones run to the under and 

 the weaker ones to the front side of the adductor; in front short nerves emerge to 

 the branchial suspenders, in which small ganglia are formed, the right one situated 

 somewhat more dorsally. 



Connected with the branchial nerve and on the base of the branchial axis a 

 thickening of the epithelium is observable, representing the osphradium. On the 

 upper sides of the small pedal ganglia are situated the statocysts, each containing 

 one statolith. 



The genital system. The sexes are separate. The specimen cut in sections 

 was a male, sexually mature, with its spermatophorous tubes filled with very minute 

 spermatids. The genital duets are paired and strongly branched, extending from 

 the top of the umbones on each side to the bottom of the intestinal pouch at the 

 sides of the intestine. 



The ramification of the genital duets is comparatively simple. From an axis 

 running from the exteriör openings in an antero-inferior direction to the foot, on 

 the one hand, and to the umbones on the other, the lobes project chiefly in a 

 frontal direction. Both organs are almost symmetrical, but on the left side the coeca 

 penetrate somewhat farther downwards, and in addition they occupy a somewhat 

 wider space in the middle part of the body, thus extending even behind the in- 



