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IOWA ACADEMY OF SCIENCE 



scribed as follows: "The specimen (55 mm. long) has the 

 characters of a female in the shape of the chelae and the ab- 

 sence of hooks on the pereipods. The male genital opening 

 is in the coxopodite of the fifth pereipod, and the first pleo- 

 pod is of the male type, although small. The second pleopods 

 are of the male type." This specimen was regarded, according 

 to the sexual orifice and the copulatory organs, as a male 

 with female characters. 



"B' 



Fig. 42. 



A. Dorsal view of crayfish showing abnormal organs. Note the absence 

 of the anterior lobes of the testes. A, small ovaries ; B, Sperm duct ; C. Pos- 

 terior lobe of the testes ; D, opening of the sperm duct in the coxopodite of 

 the fifth pereipod. 



B. "Ventral view of the same. Note the absence of the genital opening 

 on the third pereipod and the absence of the hook on the ischiopodite of the 

 .same appendage. A, Annulus ventralis ; B, Male genital opening on coxopodite 

 of the fifth pereipod ; C-D, First and second pleopods showing structures 

 characteristic of the male. 



