66 THE HALL OP SHELLS. 



" You are aware, Tom, with what tenacity 

 these abalones cling to the rocks, so they can 

 only be removed by taking the little house- 

 holder unawares and giving dextrous and sud- 

 den knocks." 



" Yes," said Tom, " the people here tell of a 

 Chinaman who, putting his fingers under one of 

 these shells in his attempt to pry it from the 

 rock, was held there by the abalone until the 

 tide came up and the man was drowned." 



" This tight hugging of the rock," ex- 

 plained the doctor, " is accounted for, I believe, 

 by the large suckerlike sole of the animal. It 

 consists of a rounded disk of muscular tissue, 

 which has marvelous power of adhesion and 

 brings not a little atmospheric pressure to bear 

 upon the shell. Like the limpet, it has a very 

 viscous secretion, which is a strong factor in 

 holding it to the rock. 



"The apertures along its dome suggest 

 round windows high up in some old castle 

 wall. They are the openings through which 

 the gills of the animal are kept in communica- 

 tion with the surrounding water. The earlier 

 openings you see are closed — filled up vrith 

 shelly matter — but some are always kept 

 open." 



As the doctor laid down the abalones, Un- 



