Central-nervous-system synonyms

The plan of the central nervous system is therefore that of the Arthropoda.

The nervous system of the medusa consists of sub-epithelial ganglion-cells, which form, in the first place, a diffuse plexus of nervous tissue, as in the polyp, but developed chiefly on the subumbral surface; and which are concentrated, in the second place, to form a definite central nervous system, never found in the polyp. In Hydromedusae the central nervous system forms two concentric nerverings at the margin of the umbrella, near the base of the velum.

By means of vibrations or shocks transmitted through the - Sub water, or by displacements in the balance or position of the animal, the otoliths are caused to impinge against the bristles of the sensory cells, now on one side, now on the other, causing shocks or stimuli which are transmitted by the basal nerve-fibre to the central nervous system.

Among the Archiannelida, in Aeolosoma and some Polychaetes, the whole central nervous system remains imbedded in the epidermis.

- Central Nervous System of Fiona (one of the Nudibranchia), showing a tendency to fusion of the great ganglia.