236 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



and dorsal to the posterior curve of the crop. This is the last 

 remains of streptoneury in Aplysia. The unpaired nerves 

 arising from the ganglion are liable to variation. The main 

 ones are : — 



1. Small vulvar nerve (vul. n.), which springs from the 

 antero-lateral portion of the ganglion and runs transversely, 

 branching mto two to innervate the sub-pa] hum and the 

 vulvar orifice. Before branching, however, it has an anastomo- 

 sis with the small tegumentary nerve (C5) from the pedal 

 ganglion. 



2. Branchial nerve (br. n.). This arises from the posterior 

 portion of the parietal ganglion. It is a stout nerve which goes 

 to the base of the ctenidium, where it swells into the branchial 

 ganglion. Just before entering the branchial ganglion a nerve 

 passes out to supply the purple gland. From the ganglion 

 are supplied the osphradium, the ctenidium, and the kidney. 



3. A small nerve to the floor of the pericardium (pc. n.). 



4. A small nerve to the spermatheca (spth. n.). 



E. Visceral Ganglion (vise. g.). 



(Represents the infra-intestinal and visceral ganglia fused.) 



The following nerves arise from the ganglion : — ■ 



1. A small nerve to the gastro-oesophageal artery 

 (g. oes. n.). 



2. A stout nerve (an. n. ) from the outer side of the ganglion 

 whose course is straight to the anal region dorsal to the visceral 

 mass. One branch ascends the anal spout and supplies the 

 muscular walls of the anus and the fleshy siphon, another 

 branch passes ventral to the rectum to the genital duct and 

 accessory glands. 



3. Genital nerve. This passes ventral to the duct of 

 the spermatheca, runs parallel to the large hermaphrodite 

 duct, and on the ventral surface of the albumen gland 

 swells into a small ganglion (gen. g.). From the ganglion 



