STRUCTURE OF THREE NEW SPECIES OF EARTHWORMS. 103 
Internal Anatomy. 
Reproductive Organs. — The most remarkable fact about 
the reproductive organs of this species is illustrated in PI. XII, 
fig. 13; that is, that the testes (t.) and ovaries (ov.) instead of 
being situated on the anterior wall of their respective segments 
are placed upon the posterior wall in close proximity to the 
funnels (/. ov.). I should have been disposed to regard this 
arrangement as abnormal had it not been for the fact that it 
occurred in all of the two or three specimens studied by me. 
The vesiculae seminales of this species are like those of 
other Acanthodrilus in their racemose character, and in the 
fact that they do not envelop the funnels of the vasa deferentia. 
It may easily be seen in longitudinal sections of the worm that 
the vesiculae, although so different in outward appearance 
from those of Lumbricus, only differ really in being branched 
instead of simple outgrowths (see Bergh 8, fig. 13, v. s *) of the 
septa. 
The atria, as is always the case with Acanthodrilus, are 
two pairs situated in the seventeenth and nineteenth segments. 
The vasa deferentia, as also appears to be the rule in this 
genus, open quite independently of the atria upon the eigh- 
teenth segment (PI. XIII, fig. 12). The two vasa deferentia 
unite just before their external orifice (c?), which is situated 
just on the boundary line between the seventeenth and eigh- 
teenth segments ; the pores are also situated in a groove which 
connects the two atrial pores of each side, and the presence of 
which is highly characteristic of the genus Acanthodrilus 
as also of Deinodrilus (see PI. XIII, fig. 3). The two 
vasa deferentia run side by side and obliquely, through the 
muscular layers of the integument to the external pores, crossing 
on their way the duct of the atrium of the seventeenth segment 
( p •). In longitudinal sections I traced the vasa deferentia 
back to the thirteenth segment, running in the longitudinal 
muscular layer and at some distance from the surface, nearly 
midway between the two surfaces of the longitudinal muscular 
layer ; after this they gradually approach the peritoneal face 
