328 THE DOLABELLINAE. 



Spermatotheca.— At the distal end of the large hermaphroditic duct, just 

 before it opens externally, it receives the duct of the spermatotheca, sp. ih., 

 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 hermaphroditic 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 

 3 mm. The large seminal receptacle, r. s, is strongly developed at the distal 

 end of the large hermaphroditic 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 i. 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 duct, 

 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, I. 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 fine 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 bUnd 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 



