A Description of three Acoela from the Gulf of Naples. 307 
the body. It is surrounded by much accessory glandulär tissue and opens 
not directly to the exterior biit into a depression formed by the exten- 
sion of the body wall to form a sheath (fig. 12, p). The follicular testes 
lie in the usuai position, dorsal to the ovaries. The vasa deferentia forni 
heavy coils on each side, and finally lead through a bladder-like cavity, 
into the penis (pi. 10, fig. 10). Unfortunately the process of copulation 
was not observed in these worms, and therefore it is impossible to deter- 
mine exactly how the spermatozoa enter the bursa seminaìis. There 
is certainly no duct leading from the region of the penis. 
The large bursa is situated immediately behind the mouth (pi 10, 
fig. 10). It possesses two curved chitinous mouth-pieces. These mouth- 
pieces are lamellate in structure (figs. 9 and 10). They lie dose to the 
sides of the bursa, with their openings directed toward the ventral side. 
In his description of ÄmpMscolops cinereus von Graff (1891) represents 
the three openings of the bursa lying dose together, the centrai one for 
the reception of the spermatozoa, the two lateral ones for the mouth- 
pieces. I have not been able to see the actual opening, but I conclude 
it is present in ÄmpMscolops fuligineus, because the spermatozoa were 
frequently seen protruding from the bursa in that region. There is a 
definite antrum femininum surrounded by accessory glands. In fig. 9 
the glandulär structure of the bursa itself can be seen. The main cavity 
is usuaìly filled with tangled balls of spermatozoa. 
c) Eelation to other Acoela. 
The systematic position of ÄmpMscolops fuUgineus is easily deter- 
mined, for it possesses a bursa seminahs and there are two genital open- 
ings present. It therefore belongs to the Family Convolutidae, and 
to the genus ÄmpMscolops because of the presence of two chitinous mouth- 
pieces, and the absence of a tail filament. Löhner has recently (1913) 
pubHshed a brief statement in regard to the position of the genus Äm- 
pMscolops. He includes in this genus Convolutidae with two or more, 
chitinous mouth-pieces opening into the antrum femininum. Under the 
genus Polychoems he puts those with two or more mouth-pieces opening 
into the body parenchyma; thus he finds the sanie essential point of 
difference between these two genera as exist between Convoluta and 
Monochoerus. 
Mitteilungen a. d. Zool. Station zu Neapel. Bd. 22, Nr. 9. 
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