E. NOMURA 



1. Body wall, septa and cœlomio corpuscles. 



The body wall consists of five layers. In the anterior part, 

 the body is almost cylindrical, but depressed on the ventral side 

 of segments X and XI ; posteriorly it is somewhat flattened. The 

 body is broadest at the middle and gradually diminishes towards 

 both ends. Segments polyannulate without exception in preserved 

 specimens, with 3-10 annuli according to their lengths. These 

 annuli are not present in life. 



1). The cuticle is very thin and can hardly be distinguished 

 from the hypoclermis under a low power. It is present all over 

 the body and is structureless. Fine cuticular processes have not 

 been observed in sections. It is worthy of note that stalked pro- 

 tozoan ectoparasites are often attached to the posterior segments of 

 the worm, and may be mistaken for gills. 



2). The extra- clitellar hypoclermis is generally 5-6 ( « thick, 

 and consists of regularly arranged, columnar cells. Their cytoplasm 

 is always exceedingly compact and finely granulated. In the 

 anterior and middle parts of the body, the nuclei are oval or 

 spherical, sometimes nucleolated, and he mostly in the basal half 

 of the layer. In the setal and posterior regions of the hypodermis, 

 the nuclei are roundish and contain always a large nucleolus. 



The hypodermal unicellular glands are rarely found among 

 the columnar cells. Before the maturation of the ova the gland 

 cells are fewer and most of them lie, as developing basal cells, 

 near the base and are of a flat conical form. The gland cells are 

 large and contain each a small amount of cytoplasm and a com- 

 pact discoidal nucleus attached to the cell wall. To the small 

 number of gland cells is due the absence of an apparent ' mud- 

 coat,' formed of fine mud particles and a cementing secretion. 



The clitellar hypodermis is present in segments XI-XII, but 



