496 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
(4) Genital ducts. In the female these are a pair of 
equally developed oviducts, which may be seen running 
below the visceral epithelium from the urinary papilla 
upwards for 12 to 24 mm., according to the size of 
the specimen. The tip of the oviduct is alone free, and 
protrudes for a short distance out from the visceral mass 
into the mantle cavity, bearing the oviducal aperture at 
its end, somewhat below the anterior end of the gill 
(fig. 11, od. ap.). In the male (fig. 8), there is a single 
genital duct—the penis—situated similarly to the left 
oviduct in the female (pen.). 
Other organs exposed on opening the mantle cavity.— 
After removing the vertical septum the following are 
seen : — 
(1) The intestine, running vertically up in the 
median line, over the liver to the anus, with the anterior . 
vena cava lying on its left side; 
(2) The ventral surface of the liver, covered by the 
visceral envelope; and 
(3) The two kidney sacs, posterior to the liver. 
Visceral envelope.—On removing the epithelium and 
the septal muscle, which envelop the visceral mass of 
Kledone, a muscular envelope external to this visceral 
mass is exposed. Over it ventrally run the visceral nerves 
(Pl. IX, fig. 69, Vise.V.). This envelope, dorsally, runs 
from the posterior border of the cerebral cartilage, to 
which it 1s attached, down to the level of the branchial 
hearts, where it becomes adherent to the muscular mantle. 
The dorsal region of the envelope is stouter than the 
ventral, and contains large widely separated chromato- 
phores, which probably show through the mantle during 
life. The thin ventral region covers over the liver and 
ink sac, but is dorsal to the rectum. It runs back from 
the ventral posterior edge of the cranial cartilage to the 
