58 THE AMPHINEURA 
phora, the renal tubes are first directed forwards and then turn 
sharply backwards to run parallel to their former course. But the 
kidneys of Neomeniomorpha are very different both in structure and 
conformation from those of the Polyplacophora ; they serve also as 
efferent ducts for the genital products, and their inner walls— 
particularly the conjoined terminal pouch—are very glandular, and 
form an organ which secretes the egg-shell. Moreover (except in 
Lepidomenia, in which they are very simple) they bear one or two 
pairs of caecal appendages on the proximal part of their course, 
the caeca nearer to the pericardium serving as sperm reservoirs. 
Nervous System.—On the dorsal side, and in front of the buccal 
bulb, there is a large supra-oesophageal nerve-mass, formed by two 
conjoined ganglia, and often provided with accessory lobes. Two 
ganglionated nerve-trunks are given off from each side of this 
Fic. 38. 
Proneomenia gerlachei, right half of the posterior part of the body, left-side view. ca.g.co, 
common median cavity of ‘the two shell-glands ; cl, cloaca; com.l, supra-rectal pallial com- 
missure ; con.p, the most posterior pedal commissure ; 3; cu, cuticula ; 5 "du. g, opening of the gonad 
in the pericardium ; gl.co, shell-gland of the left kidney ; gl.g, left gonad ; in, intestine ; o.d, 
dorsal sense-organ ; 0.g, common opening of the two reno-genital ducts ; p, foot ; per, ‘peri- 
ceardium ; 7, left kidney ; ve, rectum ; ven, ventricle of heart ; ve.s, seminal vesicle: * anterior 
limit of the junction of the two shell-glands. 
cerebral ganglion ; that on the dorsal side being the pleural, that 
on the ventral side the pedal cord. The two cords may originate 
separately from the cerebral ganglion, or may be fused at their 
origin and diverge after entering a pleural ganglion (Neomenia). 
They correspond to the homonomous cords in the Polyplacophora. 
The pedal cords enlarge to form a pair of pedal ganglia, united by 
a thick pedal commissure, and are continued posteriorly as two 
regularly varicose trunks united by transverse anastomoses. The 
two pallial cords are joined together posteriorly by a supra-rectal 
commissure, which is double in Proneomeniu sluiteri, but absent in 
Dinomenia verrucosa and Rhopalomenia indica. An ovoid ganglion is 
generally borne on the supra-rectal commissure. The pallial cord 
of either side is united to the corresponding pedal cord by more or 
less numerous anastomoses. In some forms, e.g. Paramenia, the 
pedal cords are united to the pallial some way in front of the supra- 
rectal commissure. A small anterior infra-oesophageal or stomato- 
