232 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



muscles of the bulb. A chain of small ganglia occurs along the 

 course of this branch. 



2. Anterior tentacular nerve, the nerve of the labial 

 tentacle (ant. tent. n.). This arises from the ventral side of 

 the cerebral ganglion, emerges beneath the third nerve, and 

 rims forward as a stout nerve beside the buccal mass. It has 

 two branches. The first or superficial branch is external to 

 the second or deep branch. The superficial branch runs close 

 under the skin of the labial tentacle, forking round the lobes 

 of the tentacle. Knotty thickenings often occur along it, but 

 these do not contain nerve cells. The internal or deep branch 

 divides into three, of which two supply the ventral and lateral 

 portions of the buccal cavity and are ganglionated, while the 

 third runs along the fleshy base of the labial tentacle. 



3. Posterior tentacular nerve, the nerve of the rhino- 

 phore (rh. n.). Its origin is close to that of 1 and 2, but it 

 immediately ascends dorsal to them so that it appears to be 

 the first nerve when the ganglia are exposed. Its course is 

 straight to the rhinophore. When it reaches the body wall 

 a small nerve branches off to supply the inner side of the 

 tentacle. The main nerve is ganglionated at the base of the 

 auriculate portion of the rhinophore, and from this ganglion 

 a single nerve proceeds along the inner or folded side of the 

 tentacle, branching to supply the lobes of the ear-like apex. 



4. The optic nerve (opt. n.). The presence of a com- 

 paratively large optic ganglion, attached to the cerebral 

 ganglion, would suggest a well developed eye and stout optic 

 nerve. Such is not the case, however. The eye is sunk in 

 the skin at the base of the rhinophore, and its nerve is extremely 

 slender. The optic nerve is closely attached to the nerve of the 

 ihinophore. 



Nerves 3 and 4 pass dorsal to the penis on the right side. 



5. Tegumentary nerve (teg. n. 2). It springs from the 

 postero-lateral portion of the cerebral ganglion, and supplies 



