No. G32] SECONDARY SEXUAL CHARACTERS 223 



of legs, in the female they are further forward on the 

 segment that carries the third pair of legs. 



In the summer of 1917, at Woods Hole, Miss Grace 

 Hays, while sorting out some fiddlers, found an individ- 

 ual that had a small first pair of legs like those in the 

 female", but an abdomen like that in the male. Another 

 collection of crabs was made and three other such indi- 

 viduals were found. In the summer of 1919 the col- 

 lectors at Woods Hole brought to me more fiddlers, and 

 from them more aberrant forms were obtained. It then 



seemed wort]] while to find out how often such individ- 

 uals occur in this locality. Thanks to the interest shown 

 by Mr. Wm. Procter and Mr. Alfred F. Huettner a large 

 number of crabs were collected and carefully looked 

 over. 1 As shown in the following table the number of 

 aberrant individuals was found to be about .0077 per 

 cent. 



