SEA-FISHERIES LABORATORY. 201 
THe ALIMENTARY CANAL. 
By far the greater portion of the alimentary canal les 
entirely within the proximal limb of the viscero-pedal 
mass, and may be easily dissected in a specimen hardened 
with formol by removing the muscular body-wall of one 
side, cutting through the attachment of the transverse 
muscle bundles as close to the integument as possible. 
The attachments of these to the opposite wall are then 
cut through beneath the intestine and the bundles removed, 
the digestive gland and the gonad are picked away, and 
the stomach and intestine lie exposed to view. 
The mouth (M., fig. 3, Pl. I.) is at first a wide slit 
extending across the body between the anterior body-wall 
and the anterior adductor. It is bounded dorsally and 
ventrally by the prominent upper and lower lips, the outer 
extremities of which are produced laterally to form the 
dorsal and ventral labial palps respectively. The opening 
soon contracts, so that the perforation in the muscular 
body leading into the cesophagus is oval in form. The 
latter (Al.c.1) is a short tube passing backwards and 
slightly upwards towards the posterior and dorsal part of 
the viscero-pedal mass, where it expands into the stomach 
(Al.c.2), which forms a capacious sac, Increasing in 
diameter from before backwards. The stomach is sur- 
rounded on all sides by the dark-green mass of the 
digestive gland (D.g.). This is really paired, and forms a 
thick lobe on each side Each lateral lobe, however, 
expands over the dorsal anterior and posterior sides of the 
stomach, so that it seems to nearly envelope the latter. 
If the digestive gland is carefully picked away prior to 
laying bare the stomach, two ducts may be seen opening 
into the latter. One is small, and opens on the posterior 
and dorsal margin; the other is much larger, and opens 
into the stomach at its junction with the cesophagus; it 
