GROWTH AND AGE AT MATUBITY OF THE PACIFIC RAZOR CLAM 
207 
DIGESTIVE SYSTEM 
The mouth of the razor clam has the shape of a flattened funnel and leads 
directly into a slender esophagus. The oesophagTis opens into the stomach, 
which lies directly under the hinge and in this clam is comparatively large; it 
is surrounded by a dark " liver," which secretes digestive juices into it through 
wide open ducts. The posterior part of the stomach is lined with cartilaginous 
tissue, from the bottom of which a long diverticulum extends downward to the 
lower margin of the foot. This is filled with a clear, gelatinous rod called 
the "crystalline style," containing a starch-digesting enzyme similar to that of 
the saliva. 
The intestine leads downward from the middle of the stomach and is coiled 
below the liver, from whence it follows the posterior margin of the foot upward 
through the end of the liver. Here it turns abruptly backward, passes through 
the heart, over the posterior adductor, and ends in a fleshy papilla at the base 
of the exhalent siphon. There are two dark-colored kidneys, one on either side 
near the heart cavity. 
NERVOUS SYSTEM 
The nervous system of the razor clam is very simple, consisting of three pairs 
of ganglia. The cerebral ganglia lie on either side of the mouth near the lower 
surface of the anterior adductor muscle. The visceral ganglia occupy a somewhat 
similar position on the posterior adductor muscle; they are more closely united 
than are the cerebral. The pedal ganglia are closely fused and are embedded in 
the muscles of the foot. These pairs of ganglia are connected by nerves. There 
are no special sense organs except a pair of minute statocysts, or balancing organs, 
lying on either side of the pedal ganglia. 
LOCOMOTION 
One of the most interesting things about the razor clam is its unusual ability 
to move through the sand. The foot is quite different in shape from that found 
in the soft-shell and butter clams, being elongated and nearly cylindrical instead 
of flattened. It is a very effective burrowing organ, and, unlike many others, 
the razor clam retains throughout life a high power of active movement. In 
burrowing, the foot is extended from the shell; the tip, which is pointed, is 
thrust through the sand, and, when fully extended, the tip expands, forming an 
effective anchor. The foot is then retracted, drawing the body toward this 
anchored portion. Eepetition of this action gives the clam a rapid movement. 
The mechanism for the retraction of the foot is easily demonstrated. The 
bulk of the elongated foot consists of longitudinal fibers. These are connected 
with the shell by two specialized retractor muscles (anterior and posterior), one 
of which lies near each of the large adductor muscles which close the shell. The 
combined contraction of these shortens the foot with considerable force. 
The method by which the foot is extended is less well understood. Clams taken 
out of the sand very often discharge a large amount of fluid from the tip of the 
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