408 



of the abdomen and character of the sperm- transferring appendages 

 but in the greater size of the chelae, as seen in the accompanying figure 

 which is from a photograph of the male and female. The spots on the 

 carapace of the male had the same arrangement as in the female but 

 were a little smaller in general so that more of the background showed 

 between them, that is they were not crowded as closely as in the female. 



The striking color factor was, however, the presence of blue in the 

 male and not in the female. Certain of the rounded spots had in the 

 male an intermediate area of sky-blue between the central white and the 

 peripheral red line. This blue made these spots very conspicuous. The 

 blue color was often to some extent shaded toward the centre so that 

 one was reminded of the »eye spots« on the wings of insects and feathers 

 of birds. The amount of blue was different in different spots and might 

 make but a slender rim within the red line, or nearly cover the entire 

 centre of the spot. 



To represent these spots in the photograph it was found expedient 

 to darken them with ink, so that the upper figure in the photograph 

 shows pretty acurately the number and distribution of all the spots in 

 the male that had blue in them, as none are found on the ventral face 

 of the animal, but it does not represent the amounts of blue in the diffe- 

 rent spots. It will be noted that blue spots are found on the limbs right 

 and left rather symmetrically and on the carapace with some depar- 

 tures from symmetry, which is also true of the more numerous spots 

 without blue. 



While the male is thus easily recognized by its blue rings there is 

 no evidence that this fact is of any importance to the animal. In this 

 apparently monogamous animal living protected or concealed in the 

 shell that forms its host's house it Avould be only some peculiar and 

 unknown habits that might make the blue color valuable. The real 

 significance of this concommitant occurrence of blue color and male 

 sex may not have any reference to the surface of the animal. 



As the blue color disappears in alcoholic specimens it has not been 

 seen in museum specimens and this suggests there may be many cases 

 of sexually limited coloration in Crustacea that have thus escaped notice. 

 A comparative study of live Crustacea might discover more cases of 

 such coloring and suggest lines of investigation as to their meaning. 



26* 



