THE AMERICAN NATURALIST [Vol. XLIV 



this type usually lie at the bottom of corresponding de- 

 pressions. We consider that the minute elevations on 

 the surface of the so-called pearl mark the positions of 

 tegumental glands, the only other possible conclusion 

 being that they represent extremely minute and no 

 longer functional hair-pores. In any case they prove 

 that the structure of this body tallies with that of the 

 rest of the shell. 



It may be added that between the conspicuous "cra- 

 ters" of the more prominent and functional hair-pores 

 (on the inner surface of the shell of the big toothed 

 claw), innumerable smaller granulations occur which do 

 not appear to belong to functional setse or to glands, while 

 along the lower outer margin of this claw, where the 

 setae are bunched, each elevated area has the appearance 

 of a sieve, bearing hundreds of holes. Two of these 

 areas, which correspond to very marked depressions on 

 the outside of the shell appear at the upper right hand 

 side of Fig. 4 (s. p.), close to the outer margin of the 

 toothed claw, and near its tip. The magnification, how- 

 ever, is not sufficient to show the pore-canals. The 

 hard shell of the lobster is further vertically striated 

 and horizontally laminated, and the same laminated 

 structure can be seen at the base of the body in ques- 

 tion, where a knife has been applied. 



The specific gravity of the sphere was found to be 

 1.45, and that of a part of the dried shell of a toothed 

 claw (from upper surface of propodus, near the hinge- 

 joint of a large hard-shelled individual) was 1.43. 



It is thus evident that in color, texture, structure and 

 specific gravity, the body under analysis agrees with 

 the shell, being peculiar only in its form, and in the 

 position which it occupied in the meat of the claw. It 

 is not a "pearl" in any sense, but an integral part of 

 the shell, to which it was joined at its short stem or 

 base, until the claw was broken open by the finder. 



Origin— It is safe to say that no proper pearl can be 

 formed in a crustacean, and presumably in no other 



