42 CALIFORNIA ACADEMY OF SCIENCES. 
considered as our largest earthworm, though very variable, as might be expected. 
The smallest adult worms measure about 15 inches by 3 lines, the largest again 6 
inches by 4 to 45 lines, the size appears to depend greatly on the locality and richness 
of the soil. The prostomium divides somite i to about 5 or % (fig. 180). Somites vii, 
viii, ix, are larger than the other anterior somites. The clitellar somites (figs. 125 to 
151) are large, the post-clitellar ones are very much smaller. The spermathecal 
pores are more or less conspicuous (fig. 129 spth.), sometimes hardly visible, at times 
again elevated and appearing as small round rings. They are situated just lateral to 
setee 2, but of course in the intersegmental grooves between vii / villi and yili/ix. The 
ovipores are closer together, situated a little more ventrally than sete 1, sometimes, if 
not generally, connected by a depression. The clitellum is only developed dorsally 
and laterally, the ventral part between the male pores being normal and appearing as 
considerably depressed, in hardened specimens the depression reaching as far forward 
as to the center of somite xiv or the oyipores. 
The male pores which open in line with sete 2, are situated on either side on an 
elongated papilla, which again is more or less surrounded by a circular depression, 
outside of which is seen a high semi-circular ridge, which is thicker anteriorly and 
posteriorly than laterally (fig. 25, 129). The penial setee are one pair in each 
pore, and are seen protruding through the male-pore. 
The regular setee are sigmoid, not greatly bent. The sete of the inner couples 
are closer than those of the outer couples; all the setee are in parallel rows (fig. 24). 
The nephridio-pores are difficult to view from the outside. Their arrangement is 
variable, but the majority are found outside of, or more lateral than the fourth row of 
setee. The three anterior nephridio-pores are seen in front of sete 4 (fig. 24). A 
more detailed description will be given further on. 
Setw. The ordinary sete have been already described as sigmoid. There 
are two sacs of penial sete attendant to each prostate, and opening in the same pore, 
but not in the same duct, as that organ. There is only one seta in each sac. This 
seta is sickle-like, much more curved than those in Deltania. The point is needle- 
like, and curved (figs. 122, 123). The very point is void of sculpture, but the part 
back of the point and up to the sac is sculptured as in the figure 125. The largest 
part of the seta is smooth, only showing the rings for the attachment of the muscles. 
The inner couples of setee of the clitellum are somewhat raised, though otherwise not 
differentiated. 
ANATOMICAL STRUCTURE. 
The body-wall (figs. 114, 115, 116, 117, 118). The body-wall outside of the 
clitellum shows the usual sets of layers. The innermost vascular layer, which covers 
the longitudinal muscular layer, is very thick and prominent, though not very 
crowded with blood vessels (fig. 114). Under this layer, and between it and the 
longitudinal muscles, passes the spermduct, almost throughout its length, from the 
place where the two ducts unite to the one where they rise to join the spermduct. 
This layer is less pronounced anterior to clitellum, and appears absent in the vicinity 
