432 FRANK E. BEDDARD. 
It is more usual, however, in this genus to find only two 
pairs of seminal sacs developed, those of the eleventh and 
twelfth segments ; and these usually differ from the anterior 
pairs in their racemose character ; but there are some indica- 
tions that the real number of these organs is four pairs, pos- 
sibly in all the species of the genus. The spermathece are 
two pairs situated in segments vir and 1x; each is furnished 
with a number of small diverticula. = 
A. Layardi and A. Beddardi differ from other species 
of the genus, and from all other Earthworms, by the develop- 
ment of special glandular organs connected with the sperma- 
theca. In the former species the ventral sete of the eighth 
segment are replaced by a bundle of long, greatly modified setz 
very much like those of the seventeenth and nineteenth seg- 
ments of that and other species of Acanthodrilus; connected 
with these is a pair of glandular organs (see Beddard, 7) ; in 
A. Beddardi a similar modification of the setz is met with, 
but in the ninth as well as in the eighth segment ; furthermore, 
in this species there is only a single gland appended to each 
bundle of “copulatory sete” (as they are aptly termed by 
Horst). At the time when these structures were described by 
Dr. Horst and myself there was nothing with which they could 
be compared exactly. Since then Dr. Stolé has published an 
important memoir upon certain Tubificide (88), and figures in 
Psammoryctes barbatus a pair of glands and a copulatory 
seta contained in a special sac opening into the duct of the 
spermatheca just at its external orifice. 
This structure appears to me to be quite comparable to the 
structures annexed to the spermathece in the two species of 
Acanthodrilus. We have in this a remarkable point of 
similarity between genera otherwise very widely separated. It 
is well known that in Lumbricus the sete of the segment 
upon which the spermathece open, as well as of other segments 
in the neighbourhood of the genital organs, are somewhat 
modified, but there is not in that genus or in any other such 
a remarkable specialisation of the sete as in the instances 
enumerated above. 
