54 CALIFORNIA ACADEMY OF SCIENCES. 



though they can always be made out. The clitellum comprises somites xiii to xviii, 

 though the posterior j of xii is generally also somewhat thickened. Of the anti- 

 clitellar somites vii, viii, 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/viii and viii/ix, a little lateral of the seta 2. Oviducal 

 pores in xiv 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 setpe combined in one, 0[)en 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 (xvii 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 to a line running from the 

 center of the lunar ridge parallel to the setse. The ventral part of the clitellum is 

 depressed. 



Ventral pa plU(i\ One of the most interesting featui'es 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 papillae of Perichseta, etc., 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 viii/ix. 

 One pair between ix/x. 

 One pair between xv/xvi. 

 One pair between xvi/xvii. 

 One pair between xix/xx. 



Other specimens possessed in addition to these pairs: 

 One between xx/xxi. 

 One between xxi/xxii. 



To show the variability of the.se pajiillfe 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, viii/ix. 

 One pair, ix/x. 

 One pair, xv/xvi. 

 One pair, xvi/xvii. 

 One pair, xix/xx. 



