228 THE AMERICAN NATURALIST [Vol. LIV 



At present we are entirely ignorant as to what causes 

 determine in the normal male that only one side develops 

 a big claw. The asymmetry of the fiddler appears to be 

 analogous to that of the asymmetry of snails and of the 

 one-sided operculum of certain annelids (Hydroides), etc. 

 It is generally supposed that something comes in during 

 the development of the male crab that turns the scale 

 one way or the other; and once determined the relation 

 persists during life in fiddler crabs, although in other 

 decapods, as shown by Przibram, the initial difference 

 may be reversed during regeneration if the large claw is 

 removed and the small one left. Until we get further in- 

 formation concerning these matters it would be idle to 

 speculate as to what has led in this male to two large 

 claws. 



It is interesting to note in the case of this male with 

 two large claws that it differs from the ordinary males 

 by doubling the kind of difference that distinguishes the 

 normal male from the female. It can scarcely be said to 

 be an inter-sex, for the difference is not in the direc- 

 tion of the opposite sex, but away from it. If some desig- 

 nation is called for, it might be said to be a super-male, 

 or at least an over-clawed male. 



Discussion of the Results 

 If we compare the results of parasitic castration of 

 certain decapods with the conditions described here in 

 the fiddler crab several resemblances and differences be- 

 come apparent. First in none of the cases of parasitized 

 crabs are the external genital openings affected. They 

 furnish a certain clue to the original sex of the individual. 

 Likewise in the large fiddlers the male external genital 

 pores are present, and there are no female pores. The 

 individuals have probably always been males. Whether 

 the condition of their claws is due to some disease, or 

 possibly to some internal parasite, or to a change in the 

 genetic complex, can not be stated. It is even possible 

 that it may be due to none of these, but to some "acci- 

 dent" in the development, i. e., to some change in the em- 



