of the Lima moving freely up and down, but not turning around in it. 

 Here it lives secure from prowling fish and crabs. The case is lined 

 inside with a closely woven net of byssal threads, plastered over with 

 slime. When the Lima is first taken out of its case and put into 

 a basin of sea-water, it is exceedingly active and restless, or else it grace- 

 fully careens about, with its long and thick fringe of filaments trail- 

 ing behind it. In the course of a few minutes it seems to get tired, 

 or reconciled to its prison ; and it then lies on its back, the valves 

 of its shell expanded, and reposes on its own soft, luxurious cushion. 

 The filaments (or tentacles) at first curl and entwine around one 

 another, but afterwards they are withdrawn and become contracted; 

 a circular, inner row, like a coronet, surrounds the slowly flapping 

 gills; and the outer rows fold over on each side and form a sort 

 of chevaux-de-frise. A remarkable peculiarity of Lima consists in 

 the tenacious grasp of its tentacles; sometimes when my finger touched 

 the animal, it was rapidly seized by the tentacles, as by those of an 

 Actinia (or sea anemone), and so firmly, that I have dragged the 

 Lima around the tank. It seldom let go its hold until the tentacles 

 were torn away, or as I believe, voluntarily thrown off by the animal. 

 The tentacles so detached still adhere closely to the object they have 

 grasped, their free ends twisting about as if conscious of life, and 

 they are with difficulty taken off.' 



"One of the larger bivalves belongs to the family Pinnidce, com- 

 prising the wing shells of which, one species, Pinna nobilis, attains 

 a length of two feet, and spins a fine, silken byssus by which it moors 

 its shell to some solid object. They frequently bury themselves almost 

 from sight in the sand, the shell standing erect with knife-like edges. 

 The Italians gather the byssus of this species and weave it with silk, 

 from which they manufacture gowns, caps, and other articles of wear- 

 ing apparel. You may see some of these articles in this case. The 

 shells of Pinna are triangular in shape, very thin and brittle, and 

 the hinge is without teeth of any kind. The wing shells entertain 

 a guest in the form of a little crab, which lives in the mantle and 

 gills without any apparent discomfort to the animal. Many hundred 

 years ago, Aristotle, the Greek philosopher, gave it the name of Pinno- 

 theres, or Pinna-guardian, he having believed that the crab had formed 

 an alliance with the Pinna. 



" The family Pteriidce, comprising the ' pearl-oysters,' is of great 

 interest, both scientifically and economically. At the present time 

 there are a little over one hundred species living; but the family has 

 existed since early geological times, and over a thousand species have 



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