Nervous system The central ganglion of the nervous system lies behind the proboscis sheath or septum. It innervates the proboscis and projects two stout trunks posteriorly which supply the body. Each of these trunks is surrounded by muscles, and this nerve-muscle complex is called a retinaculum. In the male at least there is also a genital ganglion. Some scattered papillae may possibly be sense-organs.
Nervous system The central ganglion of the nervous system lies behind the proboscis sheath or septum It innervates the proboscis and projects two stout trunks posteriorly which supply the body. Each of these trunks is surrounded by muscles, and this nerve-muscle complex is called a retinaculum. In the .male at least there is also a genital ganglion. Some scattered papillae may possibly be sense-organs.