INTERNAL ANATOMY. 327 
Its extreme length, transverse to the longitudinal axis of the animal is 
40.0 mm., its greatest antero-posterior width is 20.0 mm., while the thickness 
of its bulkier portion on the left reaches 14.5 mm., thinning away toward the 
right to some 7.0 mm. The dorsal surface is somewhat regularly convex, the 
ventral one quite irregular, but in general concave, as are also the anterior and 
posterior borders. The main bulk of this structure is made up of the nidamental 
and albumen glands, the windings of which are closely interlocked in the one 
common mass. An examination of Plate 5, fig. 4 will show its main relations. 
The small hermaphroditic duct, sm. h.d, reaches the right posterior angle of 
the adnexed genital mass, tapers rapidly to a third of its previous diameter, 
and passes diagonally across the lower surface to its mid-anterior margin. Here 
it curves around upon the dorsal face, forms there a broad loop and returns upon 
the ventral surface, sm. h. d’, to its posterior portion. Here the duct opens into 
a small irregular cavity, the fertilization-chamber, f. c, lying deep between the 
loops of the nidamental gland. 
Spermatocyst— Into the same cavity opens the duct of Cuvier, d. C, or 
duct of the spermatocyst. This organ, spc., lies in close contact with the ante- 
rior border of the anterior genital complex, to which it is bound by delicate 
connective-tissue. It is of elongated cylindrical form with its blind end recurved 
upon itself, and is shown in Plate 5, fig. 4 dissected free and raised slightly 
from its close attachment. 
Immediately at the union of the duct of the spermatocyst with the fertiliza- 
_tion-chamber is found the opening of the copulatory duct, c. d. This duct is 
continued to the right, uniting with the ovo-spermatic duct, ov. sp. d, to become 
the left half of the large hermaphroditic duct, J. h. d. 
Albumen and nidamental glands——Into the fertilization-chamber also 
open the duct of the albumen gland, and the proximal continuation of the spiral 
and convoluted portions of the ovo-spermatic duct, ov. sp. d. By a complicated 
plication of the walls of this duct the massive nidamental gland is formed, 
which makes up the bulk of the adnexed genital mass. 
Large hermaphroditic duct— After the union of the copulatory and the 
ovo-spermatic ducts they leave the right posterior border of the adnexed genital 
complex and continue forward in a complicated series of loops as the large 
hermaphroditic duct, J. h. d. A section across this structure shows that the 
two ducts involved in it form simply the left and right halves respectively 
of a single tube, separated from each other by thick folds from the dorsal and 
ventral sides, which meet and interlock in the centre, thus dividing the lumen 
into two nearly separate ducts. 
