150 CALIFORNIA ACADEMY OF SCIENCES. 
peculiar tissue which fills much of the ccelomie cavity. This tissue consists of large, 
more or less connected cells, very much like the ccelomic glandular cells surrounding 
so many 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 ccelomic cells, such as found in 
all earthworms. 
Nephridia. There is one pair of mega-nephridia in each somite. The 
uephridium 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 sete 4. The 
nephrostome again is as usually seen very near sete 1. There are no glandular 
ceelomic 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 isa thick 
circular valye. 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, ete. 
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. 86), 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 
valyes. 
Each valve consists of several circular rings, 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, but the outside ones run as 
the periphery in a circle. The smaller valves consist each of only one such lobe (fig. 
73a), while the large ones are composed of several (fig. 73)). 
