ZOOL.— Vol. II.] RISEN— OLIGOCH^ZTA. 233 



also a septum extending from the posterior intersegmental 

 groove on the ventral side of XII to the center of the dorsal 

 side of XII. The formula for the septa would be as follows : 



IV/V, V/VI, O, O, O, O, X/XI, XI/XII, XII/XIII, 



XIII/XIV, disregarding the double septa in XI and XII, 

 the constancy of which is not proven. 



Intestine. — (fig. 91.) The prostomium is quite large 

 and furnished with an epithelium much wider than that of 

 the body-wall, consisting almost exclusively of taste-cells 

 interspersed with a few light-cells. At the inner base of the 

 prostomium there runs all around the mouth the usual pair 

 of lip-valves capable of closing the intestinal tract against 

 the exterior. Between the lips and the pharynx there is a 

 space as wide as the lips themselves, occupied by a com- 

 mon epithelium. The pharynx is developed only dorsally 

 and is sac-like. The pharyngeal glands are large, espec- 

 ially the posterior lobe. The anterior lobes are hardly 

 perceptible in longitudinal median sections. In slightly 

 extra-median sections we see that the anterior lobes are 

 present, but small. There are five lobes, respectively 

 diminishing in size forwards, but the anterior lobe is very 

 much smaller than the one next to it — so small that it 

 readily escapes observation. 



The oesophagus extends a considerable distance behind 

 the pharynx. It is at first narrow, widening out to about 

 three times the original width and then joining the gizzards. 



The gizzards are in VII and VIII, joined by a narrow 

 bridge. Behind the gizzards the intestinal walls are fur- 

 nished with a thick, folded epithelium extending through 

 somites IX-XII inclusive. In XIII the intestine becomes 

 tubular, the epithelium not being folded and the walls being 

 narrow. This part of the intestine is perfectly straight 

 throughout, there being no bend either before or behind 

 the gizzards. 



Calciferous Diver tides. — (figs. 92, 93.) There are three 

 pairs, the same as in Benhamia, and they are of the same 

 general structure. There is only one entrance from the 



