ABALONES OF CALIFOENIA — EDWAEDS. 431 



arms on the way to the boat. Every two hours they return to the 

 launch to be warmed at the fire. It takes the united efforts of these 

 six men to equal the catch of one diver in a suit. 



The abalone has a well-developed head and a powerful, adhesive, 

 creeping foot. The shell is flattened, and the spire, which is such a 

 prominent conical structure in most snail shells, is depressed and 

 inconspicuous in this form. The last greatly enlarged whorl contains 

 the body, especially characterized by the enormous columellar muscle, 

 whose fibers run from their origin upon the muscle scar, or center of 

 the shell, into the foot. Numerous contractile tentacles arise from 

 the fringed epipodial fold, or ruff, around the base of the foot. The 

 gills, alimentary system, reproductive glands, kidneys, heart, and 

 blood vessels and the pallial and visceral sections of the nervous 

 system lie to the left of and behind the columellar muscle and foot. 

 From the mouth cavity the gullet leads backward to the enlarged 

 stomach, which is divided into two compartments, and receives the 

 digestive juices from the large digestive gland at the hind end of the 

 body. Two pairs of salivary glands pour their secretions into the 

 buccal cavity. The intestine runs anteriorly to the side of the head, 

 there turns on itself, and proceeds back to the stomach, where it again 

 goes forward^ passing through the ventricle of the heart, to terminate 

 in the anus, which opens into the gill cavity. The shell is perforated 

 toward the left by a series of openings lying above a slit in the mantle 

 fold leading into the gill cavity, whence issues a stream bearing the 

 excrement, respiratory, and excretory wastes. Three tentacular proc- 

 esses from the edges of the mantle cleft project through these holes. 

 As the animal grows the apertures; in the shell behind the respiratory 

 cavity are closed up and new ones are formed at the anterior edge. 



The head terminates in a short snout, on either side of which is a 

 somewhat slender olfactory tentacle, and slightly lateral to this a 

 shorter and broader optic tentacle. Two elongated ganglia lying 

 above the mouth cavity may be called the brain, because they form 

 the center for nerves from the eyes, olfactory tentacles, snout, lips, 

 and other parts of the head. The e5^e is a simple cup-shaped depres- 

 sion of the epithelium on the end of the tentacle. The cup is filled 

 with a gelatinous lens and it has clear and pigmented retinal cells 

 connected with fibrils from the optic nerve. The shadow of a hand 

 passing over the abalone in an aquarium causes the animal to con- 

 tract the head end of the body. Hence the abalone differentiates 

 various intensities of light, and thus possesses a primitive sense of 

 sight. The contractile tentacles running out in every direction from 

 the ruff are end organs of touch. Each has a nerve connected with 

 either the right or left pedal cord. These two centers of innervation 

 run through the middle of the foot for the greater part of its length 

 and are connected by cross fibers. They not only receive stimuli 



