BARNACLE GEESEGOOSE BARNACLES. 307 



Almost every one is acquainted with at least one kind of 

 the Barnacle shells which were supposed to enclose the 

 embryo of a goose, namely the small white conical hillocks 

 which are found, in tens of thousands, adhering to stones, 

 rocks, and old timber such as the piles of piers, and may 

 be seen affixed to the shells of oysters and mussels in any 

 fishmonger's shop. The little animals which secrete and 

 inhabit these shells belong to a sub-class and order of the 

 Crustacea, called the Cirrhopoda, because their feet (poda), 

 which in the crab and lobster terminate in claws, are modi- 

 fied into tufts of curled hairs (cirri), or feathers. When 



FIG 40. SECTION OF A SESSILE BARNACLE. Balanus tintinnabulum. 



the animal is alive and active under water, a crater may be 

 seen to open on the summit of the little shelly mountain, 

 and, as if from the mouth of a miniature volcano, there 

 issue from this aperture, from between two inner shells, the 

 cirri in the form of a feathery hand, which clutches at the 

 water within its reach, and is then quickly retracted within 

 the shell. During this movement the hair-fringed fingers 

 have filtered from the water and conveyed towards the 

 mouth within the shell, for their owner's nutriment, some 

 minute solid particles or animalcules, and this action of the 

 casting-net alternately shot forth and retracted continues 



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