264 C. L. TURNER. 



definite secondary sexual characters of the male. All four were 

 carrying eggs or embryos attached to the abdomen, making it 

 certain that they were fully functional females in spite of the 

 presence of male secondary sexual characters. These four will 

 be referred to in the descriptions as numbers 9, 10, n and 12. 

 The brood of one of the specimens was successfully reared. Eight 

 months after hatching twelve members of the brood were still 

 thriving and it is hoped that the effort to maintain and breed 

 them under laboratory conditions will be successful. 



Later in the summer of 1923 one hundred females were taken 

 from South Kinnikinick Creek a tributary of the Rock River fif- 

 teen miles south of Beloit. Among these were found seven having 

 the partial development of male secondary sexual characters. 

 These seven will be referred to as numbers 13, 14, 15, 16, 17, 18 

 and 19. 



Other streams in the vicinity of Beloit have been searched and 

 a considerable number of abnormalities in the secondary sexual 

 characters have been found. In no female individual, however, 

 has there been found any male secondary sexual character. 



The fact that this simultaneous occurrence of male and female 

 secondary sexual characters in the same individual has been found 

 only thirteen times in the entire genus Cambarus makes the 

 discovery of nineteen specimens in a single species within a 

 limited area well worth investigating. 



This same condition has been found to exist in southern Wis- 

 consin to a still greater degree in Cambarus virilis. Eighty-eight 

 per cent, of all the females taken in Delavan Lake show additional , 

 male secondary sexual characters. 



It seems likely that the conditions causing the high rate of 

 peculiarities is a local one and it is proposed to go into the mat 1 1 i 

 thoroughly and to publish results whenever a body of newdata has 

 been collected or whenever any conclusions have been reached. 



REVIEW OF LITERATURE. 



The first described instance of a truly hermaphroditic decapod 

 crustacean is that of a lobster (Honmris viifyiris) which had 

 normal external genitalia and internal organs of the m.ile <>n the 

 left side and those of a female on the right side. The specimen 



