54 CALIFORNIA ACADEMY OF SCIENCES. 
though they can always be made out. The clitellum comprises somites xili to xviii, 
though the posterior + of xii is generally also somewhat thickened. Of the anti- 
clitellar somites vii, vill, ix are thicker than the others, and as thick as the somites 
of the clitellum. All the somites are deeply segmented, except the clitellar somites 
and those anterior to iii. The external pores are situated as follows: Spermathecal 
pores, two pairs, between vii/yiii and vili/ix, a little lateral of the seta 2. Ovidueal 
pores in xiy in front of seta 1, generally in a slight depression, bordered by a swelling 
of the body-wall. The male pore and pore for penial setee combined in one, open in 
line with seta 2 in xviii. The male pore is characterized by being situated on an ele- 
vated papilla more or less oblong. This papilla is surrounded by a circular depression 
which encroaches on the two adjoining somites (xvil and xix), and this depression 
is again surrounded by a lunar ridge, open ventrally, and extending from the center 
of xvii to the center of xix, thus reaching slightly outside of the clitellum (fig. 129). 
The clitellar glands do not extend further ventrally than toa line running from the 
center of the lunar ridge parallel to the sete. The ventral part of the clitellum is 
depressed. 
Ventral papilla. One of the most interesting features of this genus are the inter- 
segmental glands occurring on the ventral side and which in our present species are 
paired. They have possibly the same general function as the tubercula pupertatis of 
the true Lumbricids, or the ventral papille of Pericheta, ete., which latter they 
greatly resemble, but unlike the former they are variable in position, sometimes oc- 
curring to the number of as many as seven pairs. In other specimens again they are 
reduced to one solitary tubercle, situated on one side of the ventral median longitud- 
inal line. The most common form is as follows: 
One pair between vili/ix. 
One pair between ix/x. 
One pair between xy/xyl. 
One pair between xvi/xvii. 
One pair between xix/xx. 
Other specimens possessed in addition to these pairs: 
One between xx/xx1. 
One between xx1/xxii. 
To show the variability of these papille I give their places in a few individuals 
picked out at random, and I only add that other variations occur, as may be expected, 
from what is shown here. All these specimens were taken the same day and at the 
same locality: 
No. 1. One pair, vili/ix. . 
One pair, 1x/x. 
One pair, xv/xvyi. 
One pair, xvi/xvii. 
One pair, xix/xx. 
