No. I.] SENSE-ORGANS OF LUMBRICUS AGRICOLA. 217 



Summary. 



The foregoing observations seem to me to warrant the follow- 

 ing statements of facts : 



1. The epidermis, exclusive of the sense-organs, contains 

 three kinds of cells, arranged in two layers : an outer layer of 

 gland-cells and supporting cells, and an inner layer of small 

 basal cells. 



2. The supporting cells and gland-cells are not connected 

 by intermediate forms, but both are connected by intermediate 

 forms with the basal cells. 



3. The epidermis is covered exteriorly by a cuticula com- 

 posed of at least two layers of fibres. 



4. The epidermis is separated from the circular muscles by 

 a basement-membrane. 



5. There are nei've-fibres ending freely between the cells of 

 the epidermis ; these fibres are more numerous among the 

 gland-cells. 



6. These intraepidermal fibres arise as efferent fibres in the 

 central nervous system, and those in each half of a metamere 

 come from the corresponding half of a ventral ganglion, or 

 cephalic ganglion and aesophageal ring if in the prostomium 

 and first metamere. 



7. The efferent nerve-fibres leave the ventral ganglia by 

 each of the three great paired nerves which arise from a gan- 

 glion, and reach the epidermis by the regular course of these 

 nerves. 



8. Each of these nerves passes through the longitudinal 

 muscles to the inner surface of the circular muscle-layer and 

 divides into a dorsal and a ventral ramus. 



9. These rami pass between the two muscle-layers to the 

 mid-dorsal and mid-ventral line. The rami of each pair of 

 nerves thus form a nerve-ring which is incomplete dorsally and 

 ventrally, and three of these rings thus exist in each meta- 

 mere. 



10. From these three nerve-rings, epidermal nerves pass 

 through the circular muscle-layer to the epidermis. 



