118 INVERTEBRATE ZOOLOGY 
white nerve collar, the dorsal portion of which is the brain. If, 
however, the animal died in a retracted condition the pharynx 
may have slipped back through the nerve collar, which would 
then encircle the forward end of that organ. Note the two 
white, leaf-like salivary glands which lie close against the wall 
of the stomach, and trace their ducts forward to the pharynx. 
Lying above and across the cesophagus is the white cylindrical 
penis, which will be seen to extend from the genital pore at 
the right of the mouth and to bend sharply on itself. The 
bend of the penis is connected by a long retractor muscle to 
the dorsal body-wall. Find it; cut it and pin the penis on the 
animal’s right. Note the broad, glistening retractor muscle 
connecting the pharynx with the ventral, posterior body-wall. 
Notice its shape; with strong forceps pull it loose from the 
pharynx and entirely remove it. Also beneath it, note the still 
larger retractor muscle running from the forward end of the 
head back to the same locality. What is the function of these 
different retractors? The dark-colored sheaths and the retractor 
muscles of the tentacles will also be seen; trace these muscles 
to their origin. Find the nerve which passes from the brain 
into each tentacle. 
Separating the delicate filaments connecting the stomach with 
the surrounding organs, and pushing it and the cesophagus to 
the animal’s left, find the large nervous mass which forms the 
ventral portion of the nerve collar, and the nerves radiating 
from it. It is an agglomeration of ganglia, being made up 
principally of the pedal and the visceral ganglia. Press the repro- 
ductive organs to the animal’s right and pin them down. The 
receptaculum seminis, a small spherical body the size of a shot, at 
the end of a long tube, will be found in a bend of the intestine, 
from which it must be separated. 
We turn now to the other end of the intestine. Trace the 
rectum from the anus to the point where it is surrounded by 
the liver and carefully dissect away the integument which covers 
