150 CALIFORNIA ACADEMY OF SCIENCES. 



peculiar tissue which fills much of the coslomic cavity. This tissue consists of large, 

 more or less connected cells, very much like the coelomic glandular cells surrounding 

 so man}' nephridia. These cell masses are more or less diffuse, and appear not dis- 

 tinctly connected with any of the interior organs of the body. Among these cells 

 are found scattered about large masses of spermatogonia, all in about the same stage 

 of development. There are also numerous small free coelomic cells, such as found in 

 all earthworms. 



Nephridia. There is one pair of mega-nephridia in each somite. The 

 nephridium is very large, projecting above the lateral line of the body. The nephro- 

 pores — at least some of them — are seen outside of or more dorsal than setse 4. The 

 nephrostome again is as usually seen very near setae 1. There are no glandular 

 coelomic mantles on any of the nephridia. The anterior fold is much wider then the 

 posterior one. The windings are very deep and twisted, and-the spur generally sigmoid. 

 The outlet duct, which is tapering towards the pore, is much darker than the other 

 ducts. Its prolongation into the anterior fold forms there the central wider canal, 

 which is also darker than the other two. The canal in the bridge continues forwards 

 and upwards through the anterior fold, and is there the posterior one of the three 

 canals. 



Vascular system. The ventral and dorsal longitudinal vessels are both single. 

 There are connecting vessels in somites vii to xii." In x, xi and xii, these vessels are 

 very large, and take the form of so-called hearts. Each heart consists of four or five 

 links, increasing in thickness upwards. Between each two links there is a thick 

 circular valve. Similar valves are seen also in the dorsal vessel at the junction with the 

 hearts. At the base of some of the valves are seen two rows of very large cells, the 

 nuclei of which are about 3 to 4 times larger than the nuclei in the valve cells (fig. 

 83). All the valves in the hearts point downwards or ventrally. There are no 

 glandular cells in the vessels, such, for instance, as are found in Pontodrilus, etc. 



Posterior to the hearts we find long, tubular connecting lateral vessels, between 

 the dorsal and ventral trunks, in the anterior part of each somite. These vessels, one 

 pair in each somite (fig. 8G), are of even thickness throughout, but with two short 

 knob-like diverticula, one above the other, about equal distances from each other and 

 from the longitudinal vessels. Both the dorsal vessel, as well as the laterals, are 

 thickly covered with coelomic chloragogen cells of a yellowish opaque color. These 

 cells do not cover the ventral longitudinal vessel. These lateral vessels contain no 

 valves. 



Each valve consists of several circular ring.s, each containing a number of 

 muscular strands enclosed within a common membrane, in longitudinal sections of 

 the vessel most of the nuclei lie parallel with each other, luit the outside ones run as 

 the periphery in a circle. Tiie smaller valves consist each of only one such lobe (fig. 

 73a), while the large ones are composed of several (fig. 736). 



