TWO AQUATIC OLIGOCILETES. 7 



gland cells are large and contain a single nucleolus, usually lying 

 near the base. 



3). On the circular muscle layer I have but little to add to 

 the description of Hatai. I must however note the presence of 

 compact granular bodies between the circular muscle fibres, which 

 take up orange G in Malloey's method. In eosin stained sec- 

 tions they appear as diffuse granules. Their nature remains total- 

 ly unknown to me. 



4). Immediately under the circular muscle layer run the 

 longitudinal muscle fibres parallel to the body axis. It is divided 

 by lateral lines into two bundles, the dorsal and the ventral 

 (Hatai). Sometimes the boundary between the two disappears. 

 This layer is very weakly developed at the posterior end of the 

 body. 



5). The peritoneal layer consists of large vesicular cells, and 

 stands in close relation to the longitudinal muscle layer. It is 

 strongly developed in segments IV- VIII, but less well in the 

 prostomium and the posterior segments of the body. The cells 

 of the peritoneum are irregular in shape, and the layer always 

 presents a smooth surface toward the body cavity. The nuclei 

 are large and sometimes nucleolated. The cells of the lateral 

 lines are richer in cytoplasm than the neighbouring peritoneal cells. 



2. Set^: and Seta-bundles. 



The sigmoid setae of L. gotoi are nodulate and bifurcate at 

 the distal end. The branches appear almost equal under a low 

 power, but unequal under a higher. In the anterior parts of the 

 body the upper branch is larger than the lower, but in the 

 posterior parts the reverse is the case. The nodulation is smooth. 

 A seta passes through the cuticular layer at a point which 

 lies between the nodule and the tip. In the anterior parts 

 of the body the setae " are arranged in bundles in longitudinal 

 lines corresponding to the four corners of a squarish cross-section 

 of the body " (Hatai), but in the posterior parts the dorsal and 

 the ventral seta-bundles of each side approach the lateral line 



