56 OPISTHOBRANCHIATA OF BRAZIL 



and 0.1 mm. in diameter. The spermatotheca is thin walled, 

 spherical and i.o mm. in diameter. A very slightly developed 

 system of folds in the wall of the large hermaphroditic duct, 

 close to and above its external opening, probably functions as a 

 vulvar gland. 



The spermatic portion of the duct is continued forward 

 beyond the external opening as a deep groove along the side of 

 the animal, downward and forward, to the penis opening, sit- 

 uated as usual on the right side of the head, just below the 

 anterior tentacle. The penis is inclosed in an evertible, muscular 

 sack, the posterior end of which is attached to the foot and the 

 lower body wall by two groups of retractor muscles, a dorsal and 

 a ventral set. The spermatic groove is continued along the inner 

 wall of this sheath to its base, where the penis proper is attached, 

 and is thence continued forward along the side of that organ to 

 its tip. In its retracted condition the penis sack measures 7.0 mm. 

 Its inner wall is thrown into a series of longitudinal folds, between 

 two of which the spermatic groove is inclosed. This and the 

 adjacent folds are sprinkled with brown pigment. 



The proximal end of the sheath is occupied by the retracted 

 penis, a slightly flattened, conical, muscular organ, 0.6 mm. in 

 diameter at the base, and ca. 2.5 mm. long in its retracted con- 

 dition. Along its whole length extends a deep furrow, the 

 spermatic groove, continuous at its base with the groove upon the 

 inner surface of its sheath. No trace can be made out of any 

 armature upon any portion of the penis or its sheath, nor is there 

 any specialized glandular area present. 



The Organ of Bohadsch. 



The organ of Bohadsch, or hypobranchial gland, is spherical, 

 somewhat flattened in form, of a whitish color, and has a diameter 

 of 4.0 mm. In general aspect it presents the appearance of a 

 close bunch of grapes, its surface being nodular in form, corre- 

 sponding to the very large gland cells of which it is constituted. 

 The gland opens externally by a single large duct, the orifice 

 with tumid margins being situated upon a conspicuous elevation 

 below the ctenidium and behind the reproductive opening. 



Large gland cells similar in form to those of the hypo- 

 branchial gland are also found scattered in the mantle margin, 



