290 NATURAL HISTORY. [CH. XXI.' 



acquainted with these crabs, since he says, " There 

 breed in some shells white and very small crabs ; 

 the greatest numbers are found in that species of 

 muscle which have the shell protuberant ; next in 

 that of the pinnae, whose crab is named pinnotheres. 

 They are also found in cockles and oysters. These 

 little animals never grow in any sensible degree, 

 <and the fishermen imagine that they are formed at 

 the same time with the animal they inhabit." He 

 likewise supposed that their lives are so dependant 

 upon each other, that if the muscle loses its little 

 crab, both shortly afterward perish. " The pinna," 

 according to Pliny, " is never found without its com- 

 panion, which is a little shrimp ; in some places a 

 small crab which bears it company, in order to par- 

 take of its food. The pinna gaping wide, and show- 

 ing her naked body to tempt the little fishes, they 

 soon make their approaches, and, when they find 

 they have full license, grow so bold as to enter in 

 and fill it ; this being seen by the guardian shrimp, 

 by a slight rap he gives the signal to the pinna, who 

 thereupon shuts her shell and suffocates whatever 

 it encloses, giving a share of booty to her com- 

 panion." Oppian still more absurdly supposed that 

 the pinnotheres, finding the shells of the bivalve 

 open, throws a small stone between them to pre- 

 vent their closing, and so enables it to devour the 

 inhabitant ; while Hasselquist as ridiculously tells 

 us, that the crab goes out to cater for the pinna, 

 and, when it returns, cries out for the shell to be 

 opened, which the grateful inhabitant immediately 

 complies with. 



