2i8 LANGDON. [Vol. XL 



1 1 . The efferent nerve-fibres of these epidermal nerves pass 

 through the basement-membrane and form a subepidermal net- 

 work, 



12. From this network, the intraepidermal nerve-fibres pass 

 between the cells of the epidermis. 



13. In the epidermis are sense-organs, each of which is com- 

 posed of a group of sense-cells covered by a layer of modified 

 supporting cells. In the base of each organ are usually a few 

 small basal cells. 



14. These sense-organs are also present in the epithelium 

 lining the buccal cavity. 



15. The sense-cells taper toward both ends ; the outer end 

 of each cell extends into a fine hair which passes through a 

 pore-canal in the cuticula above it and projects beyond the 

 latter ; the basal end of each sense-cell is always produced 

 into a sensory nerve-fibre. 



16. The sense-cells are the only cells with which the sensory 

 fibres are continuous ; they are therefore ganglion-cells. 



17. The sensory nerve-fibres pass along the basement-mem- 

 brane to the nearest epidermal nerve. These fibres then take 

 the same path to the central nervous system that the intra- 

 epidermal fibres took coming from it, and they enter a ven- 

 tral ganglion by each of the three nerve-roots on their own 

 side of the metamere. 



18. Most epidermal nerves, each nerve-ring, and each nerve- 

 trunk thus contain both efferent and afferent (sensory) nerve- 

 fibres. 



19. In the ventral ganglia each sensory fibre divides into 

 two branches; one passes caudad, one cephalad ; each ends 

 freely in the next ganglion. 



20. The sense-organs are distributed over the entire surface 

 of the body, but are most numerous and largest at each end. 



21. In most metameres a cephalic and a median zone of 

 larger organs may be distinguished. 



22. A nephridial group of small organs occurs around each 

 nephridial pore. 



In view of the conflicting accounts of the sensory structures 

 in the epidermis of Lumbricus, I have thought it best to 



