I04 CALIFORmA ACADEMY OF SCIEMCES. [Proc. 3D Ser. 



A cross-section of a calciferous diyerticle shows it to be 

 composed of layers and hexagonal chambers rather regu- 

 larly arranged in rows. Between each chamber there is a 

 tiny blood-sinus. This blood-sinus surrounds the glands on 

 all sides, but it is larger at certain points. On the exterior 

 of the diverticle we find blood-vessels with distinct walls. 

 On the dorsal side of the diverticle the blood-vessels are 

 covered by chloragogen cells which are characterized by the 

 manner of their attachment. Instead of being affixed by a 

 single spur, they adhere to the vessels by means of several 

 narrow projections (fig. 24). Each diverticle enters the 

 intestine by a separate ciliated duct, the ciliation continuing 

 some little distance into the diverticle (fig. 25, Jf). The 

 blood-vessel supplying the diverticle is directly connected 

 with the large median, dorsal vessel, a section through this 

 part showing the two vessels to be continuous and even and 

 without valves. 



There is a continuous blood-sinus in the sacculated intes- 

 tine in the clitellar somites, which varies greatly in thickness. 

 The blood is never found crystalized, as, for instance, in 

 S^arga n oph ilus . 



In somites XVI and XVII the muscular layer of the 

 intestine is considerably increased in thickness, and is 

 about three times as wide as usual. The sacculated intes- 

 tine commences in XVIII. The intestinal epithelium in 

 somites XVI and XVII is strongly ciliated. 



Typ/iloso/e. — (figs. 36 and 37.) This organ is large, 

 being sometimes twice as long as the diameter of the intes- 

 tine. It is twisted and folded, but always dorsal. The 

 blood-sinus occupying the center of the typhlosole is at 

 certain intervals enlarged, forming globular or oval cham- 

 bers. The epithelium of the typhlosole consists of rather 

 short cells of the same nature as the cells of the intestine 

 proper. The central blood-sinus in the typhlosole is con- 

 fined by a distinct and nucleated membrane (fig. 36 5). 

 The typhlosole consists of an enormously enlarged epithe- 

 lial fold with a central blood-vessel, and is thus not a mere 

 fold of the whole intestine, as for instance in Al/olodop/iora, 



