UONTRIBUTIONS TO THE ANATOMY OF EARTHWORMS. 431 
Penial sete are present on both the seventeenth and nine- 
teenth segments as in most other species of Acanthodrilus, 
but not in A. multiporus; one of these setz is displayed 
on fig. 17; it is an immature setz, showing the cell out 
of which it has been formed. Close to its base, one on 
each side, are two other cells which would doubtless have 
developed two other setz; these are surrounded by a thick 
muscular coat which forms a continuous investment of the 
setze. I have been unable to procure a fully developed penial 
sete for figuring, —the point was broken off in every case. The 
mature penial setz are of a deeper yellow colour than the 
immature ones. 
The seminal sacs are two pairs attached to the anterior 
wall of segments x1 and x11; they have the racemose character 
which is usually seen in this genus. Besides these there are a 
pair of solid bodies with an oval contour attached to the 
posterior wall of segments 1x and x. A microscopic examina- 
tion of these showed that they are also seminal sacs ; groups of 
developing seminal cells were contained in the spaces of the 
meshwork, formed of fibroid tissue; there were also numerous 
Gregarines, the presence of which is so characteristic of the 
seminal sacs of Harthworms. There are thus four pairs of 
seminal sacs of which the anterior two are outgrowths for- 
wards of the septa, separating segments rx—x and x—x1; the 
posterior two are backwardly directed outgrowths of septa x— 
XI, XI—x11. This arrangement agrees with that of the seminal 
sacs of Allolobophora fetida (Bergh, 12); there appears 
to be no median unpaired sac developed such as is found in 
Lumbricus, Microcheta, and even in certain species of 
Acanthodrilus (e. g. A. Beddardi, Horst, 24). In my 
description of A. Layardi (7) I was doubtful about the nature 
of a pair of bodies attached to the posterior wall of segment x. 
It is now clear that these structures are in all probability 
seminal sacs ; in A. capensis I have called attention to a pair 
of problematical structures attached to the posterior septum of 
segment 1x. I am now inclined to think that these may 
represent the first pair of seminal sacs of A. antarcticus. 
