6 S. HATAI. 



The sehe are simply sigmoid and furcate at the end, and are arranged in bundles 

 in longitudinal lines corresponding to the four coi ners of a squarish cross-section of the 

 body. They are present from the second segment and their position in each segment 

 is rather posterior than middle. Each bundle consists of 6 setae in tbc anterior seg- 

 ments and two in the posterior, while there are 2 — 5 in the middle portion. Besides 

 these setœ, the setigerous sac contains one or two young setse. 



Body wall. — The body wall consists of five layers, as in other Limicolae and pre- 

 sents nothing peculiar. The cuticle is very thin and covers the whole body ; im- 

 mediately under it lies the hypodermis of columnar cells. These are larger near the 

 two ends of the body than in the middle, and there are some glandular cells. The 

 nuclei lie near the middle of the cells. In the clitellum the hypodermis is also one 

 layer thick, as is the case in all Limicolae. The cells are larger and taller than in the 

 other parts and very glandular. The nuclei lying near the base of the cells are com- 

 paratively small and are oval in shape. The clitellum develops only during the 

 breeding season, and no trace of it can be detected at other times. The younger 

 specimens are entirely destitute of it. The circular muscle layer lies under the 

 hypodermis, and is unequally developed in different parts, being thickest in the anterior 

 portion and especially in the prostomium, and thence gradually becoming thinner 

 posteriorly. The longitudinal muscle layer is very well develojted and stands in close 

 relation to the circular muscle layer, and in some organs such as the penis, the setige- 

 rous sacs, and the septa, the layers mingle with each other, so that it is impossible to 

 distinguish them. It is generally most developed in the region of the genital or- 

 gans, and is thinner in the posterior than in the anterior portion. The longitudinal 

 muscle layer is divided by lateral lines into two bundles, the dorsal and the ventral. 

 At the two ends of the body, however, they fuse with each other. The innermost 

 layer of the body wall is the ccelomic epithelium, the cells of which are large and 

 botryoidal in shape. The nuclei are large and the cells are glandular, like hepatic 

 cells. In most Limicola? this layer is luxuriantly developed and fills a considerable 

 portion of the body cavity ; but in the new species it is less developed, except at the 

 anterior portion. Two pairs of septa] glands, perhaps continuations of the ccelomic 

 epithelium, are attached to the posterior faces of septa VII/VIII and VIII/IX, on 

 either side of the median line. The form and size of their cells are closely similar to 

 those of the peritoneal cells. These cells are aggregated around one axis. The axis 

 is a continuation of the peritoneum and originates a little in front of the ventral setre 

 and is in the same longitudinal line with the latter. There are no external openings 



