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 

 fopn 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 b^ two 

 conjoined ganglia, and often provided with accessory lobes. Two 

 ganglionated nerve -trunks are given off from each side of this 



Pio. 



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 ; d, cloaca ; com.l, supra-rectal pallial com- 

 missure ; com.p, the most posterior pedal commissure ; cu, cut icula ; 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 ; o.g, common opening of the two reno-genital ducts ; p, foot ; per, peri- 

 cardium ; r, left kidney ; re, 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 Proneomenia 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- 



