OF CONCHOLOGY. 17 



shaped prostatic gland about midway of the body, it is pro- 

 longed to the penis. 



The latter is long and larger at its posterior extremity, grow- 

 ing more filiform anteriorly. The foramen opens on the side of 

 the neck, just behind the right eye, and is of extreme minuteness. 

 A slender retractor muscle is attached to the posterior end of 

 the penis, and at its other extremity to the vas behind the pros- 

 tate. The protractors are on the right side of the penis, shorter 

 and stouter than the retractor. 



Special Organs. The specimens were so much contracted by 

 the alcohol that no auditory capsule was visible. The eyes are 

 minute, oval and black. The liver occupies nearly half of the 

 visceral cavity. Part of it was a light brown, and part was 

 whitish. No differences of structure or line of separation could 

 be made out under a very high power. 



Two small pear-shaped salivary glands are attached to the 

 upper posterior surface of the buccal mass. 



In the form of the verge, the renal organ, lung, muscular 

 bands and other particulars, the general structure of this mollusk 

 recalls Melampus, as figured by Souleyet. 



Sabitat. Close to high water mark on the rocky beach be- 

 tween Point Pinos and Point Cypress, near Monterey, Cal., I 

 noticed a colony of forty-eight individuals. They were stationed 

 pretty close together, on the rounded under side of a large, per- 

 fectly clean, granitic boulder. In calm weather and during ordi- 

 nary tides they would have been dry at high water. 



While refreshing myself after my morning tramp, I sat down 

 on the beach, as the tide was falling, and watched the colony. 



As long as the rock on which they were remained damp, they 

 continued with the margin of the shell firmly applied to it. The 

 shells were notched and emarginated to correspond with the ru- 

 gosities of the stone, and adhered to it so firmly as to be im- 

 movable, unless great force was applied. 



There was absolutely nothing on the rock which could have 

 supplied them with food. 



As soon as the boulder became dry, under the hot sun, I per- 

 ceived a simultaneous motion in the colony. Each shell was 

 raised above the surface of the stone, the head and foot were 

 protruded, and the orifice of the pulmonary cavity was expanded. 

 They were evidently enjoying the warm air. Some of them be- 

 gan to move, and I thought that they were about to descend to 

 the pebbles below, where an abundance of soft green algoe offered 

 an inviting repast. Their motions were so slow and my time so 

 limited, however, that I made a prize of the whole colony with- 



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