II. The buccal ganolia are juxta-posed, but yet distinct and not fused together as van 

 Beneden ') pretends. As to their exact shape and the nerves I may refer to Souleyet ') 

 and Pelseneer *). 



III. The pedal ganglia have been accurately described by Pelseneer ; I have only to remark 

 that in Pneumonoderiiia and Spo7igiobranchaea the anterior jjedal commissure (PI. V, 

 fig. i25,(r/>.) is rather long and bent into a sharp angle. 



Here too many nerves may be distinguished (fig. 125). 



From the anterior side of each pedal ganglion arises a strong nerve (8), ramifying 

 into the foot. Pelseneer has seen two nerves, somewhat smaller, the lateral of which inner- 

 vates the fins, the median the foot. 



From the lateral side, a little more ventrally two nerves proceed (9, 10). The 

 lateral nerve anastomoses with a branch of the median one ; this fact seems not to have 

 been observed yet. 



A little posterior to these nerves the rather strong cerebro-pedal connective {a) 

 branches off. 



From the posterior side of each ganglion, again two nerves issue (11, 12) which pass 

 to the fins; the lateral nerve soon divides into three, one of which is connected with the 

 median by an anastomosis. Pelseneer notes three nerves, the outer of which anastomoses 

 with a nerve of the pleural ganglion ; this anastomosis is also shown by Souleyet. Perhaps 

 it has escaped my notice, but at any rate the anastomosis between the two pedal nerves 

 has been mentioned by Souleyet *) only. According to Pelseneer, the posterior pedal 

 nerves innervate the cervical region ; I believe, however, that they pass to the fins. 



A pleuro-pedal connective is not visible externally, as the two ganglia are placed 

 very close together. 



IV. The pleural ganglia are the smallest of all and almost circular. A strong connective goes 

 from the posterior side to the visceral ganglia (fig. 124, //z^), while from the anterior 

 dorsal side the cerebro-pedal connective proceeds ((5). At the point of origin of this connective 

 two nerves arise (13, 14), innervating the neck. Pelseneer has only seen the outer nerve; 

 I have already told, that the anastomosis, mentioned by him, with a pedal nerve, has not 

 been observed by me. 



V. The visceral ganglia (fig. 124,1') are remarkable by their asymmetry, the left being the 

 larger. Just where the connective to the pleural ganglia arises, three nerves (15, 16, 17) 

 originate, supplying the visceral sac; a branch of the right lateral nerve innervates the 

 osphradium. From the left visceral ganglion (and not from the right as Pelseneer says, 

 through a slip of the pen) two nerves pass to the viscera (18, 19). Pelseneer records only one 

 visceral nerve from each ganglion to the envelopment of the body; besides, these nerves arise, 

 according to him, from the ganglion itself, and not from the transition into the connective. 



1) Recherches anatomiques sur le Piiciimotfcrmoii violaccum d'Oib., Mem. ,-\caci. Sci. Hrux., vol. XI, p. 46, pi. 1, fig. 3. 



2) Op. s. c, p. 269, pi. XV, figs. 31, 33, 3S. 



3) Op. s. c, p. 44—45- 



4) Op. s.c, pi. XV, fig. 37. 



