NEW ENGLISH GENUS OF AQUATIC OLIGOCH^TA. 161 



cation is crescentic^ with the concavity forwards. This dorsal sac 

 is lined by very tall, narrow, ciliated cells (fig. 17) pressed 

 close against one another ; the nuclei are at different levels, 

 though I believe there is only one row of cells ; the cells are 

 taller and narrower than those lining the floor of the pharynx. 



In many earthworms which I have examined from this 

 point of view the floor of the pharynx is cuticulated (see my 

 paper on " Eminodrilus " in ' Journ. Roy. Micr. Soc.,' 1891, 

 pi. iii, fig. 10; pi. iv, fig. 11), only the dorsal sac-like out- 

 growth being ciliated. 



The oesophagus, as the fig. 13 shows, is nipped by the septa; 

 it is lined by cells similar to those on the floor of the pharynx, 

 but rather shorter and less granular. 



This region of the gut is hidden, when viewed from above, by 

 three paired white masses, the salivary glands {sal. gl.), which 

 are in Somites iv, v, vi. These have the usual structure which 

 I have described for Eminodrilus (loc. cit.), and the anterior 

 ones at least are closely connected to the pharynx, with which 

 they probably communicate. 



The lining of the intestine is represented in fig. 18. The 

 cells are much shorter than those of the oesophagus, and most 

 of them are dilated distally, where the protoplasm is modified 

 to form a bright refracting and deeply stained border; beyond 

 this is a light refracting edge, which appears in some of my 

 sections to be a cuticle, but in others exhibits a fine striation. 

 I believe that the intestinal epithelium is, as in other Oligo- 

 chaetes, ciliated, and that 'owing to the mode of preservation 

 the cells have become fused or otherwise rendered indistinct. 



In broken sections the shape of the epithelial cells is well 

 seen, and they are distinctly broader at the outer end ; hence, 

 when in situ, there appear gaps between the cells. This I 

 suggest is due to the shrinkage caused by reagents, occurring 

 unequally ; the modified striated border shrinking very little, 

 the lower end shrinking much. 



§ The nephridia are very distinctly pink in a freshly 

 opened worm, owing to the rich plexus of blood-vessels around 



