328 THE DOLABELLINAE. 
Spermatotheca.— At the distal end of the large hermaphroditie duct, just 
before it opens externally, it receives the duct of the spermatotheca, sp. th., 
and also dilates anteriorly into a blind sac, the seminal receptacle, r.s. The 
spermatotheca is a large pear-shaped sac, with thin walls, lying close in front 
of the adnexed genital complex. Its slender duct is given off from the left — 
side, passes backward and to the right, closely attached to the dorsal wall of 
the body, and opens into the left side of the large hermaphroditie duct, 16.0 
mm. before the external opening of the latter is reached. The total length of 
the duct of the spermatotheca is ca. 26.0 mm., its diameter ranging from 2 to — 
3mm. The large seminal receptacle, r.s, is strongly developed at the distal — 
end of the large hermaphroditie duct. Its lumen is strongly glandular, the walls 
being thrown into a considerable number of high longitudinal folds which dwindle ~ 
away and disappear as the large opening is approached by which the receptacle 
communicates with the vaginal portion of the copulatory duct. 
External spermatic groove and penis— The common external genital ori- 
fice (Plate 4, fig. 3) is located in front of the middle of the ctenidium and directly 
below it. In Plate 5, fig. 4 its position in relation to the internal reproductive 
apparatus is indicated by the cut edge of the integument at 7. It presents 
two incompletely separated openings, bounded by strongly developed margins. — 
The posterior one of these is that of the vaginal portion of the copulatory duet, 
the more anterior one, the ovo-spermatic duct is continued forward by the 
external spermatic groove, at first wide, but rapidly narrowed by its approach- 
ing sides (Plate 4, fig. 3, l.r.). This ciliated furrow emerges dorsally from the — 
pallial cavity, between the anterior ends of the parapodia (Plate 1, fig. 1), is — 
continued along the median line of the dorsum to just behind the rhinophores, 
then curves to the right, below the base of the rhinophore of that side and passes 
obliquely downward and forward along the side of the head to the external 
opening of the penis-sac, behind and near the base of the right anterior tentacle. 
This organ is in the form of a blind sac or sheath of the penis, or glans proper, 
which is borne within at the bottom of its closed proximal end. The sheath 
is located between the right side of the pharyngeal bulb and the retractor muscles — 
of the head and its proximal end is sharply recurved dorsally. Its total length 
is ca. 50.0 mm., the diameter varying from 4.0 mm. in the anterior half to 6.0 
mm. in the posterior portion. A strong retractor muscle terminates its posterior 
end, while two broad flat protractor muscles arise along the anterior dorsal 
and ventral margins of the sheath. The three muscles are inserted in the 
lateral body-wall. Into the external opening of the sheath the deep spermatic 
