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ILLINOIS ACADEMY OF SCIENCE 



copulatory cap, is formed by the hardened secretions of 

 the cement gland of the male during the act of copulation. 

 Not all fertilized females carry this copulatory cap for 

 after a time it is apparently rather readily discarded. It 

 seems evident that the spines surrounding the genital 

 orifice of the female aid in holding this copulatory cap in 

 position since they become embedded in the substance 



Corynosoma constrictum VanC. 



Fig. 7. Posterior region of male with copulatory apparatus fully 

 retracted within body. 



Fig. 8. Posterior region of male showing position of genital 

 spines when posterior extremity is slightly protruded. 



Fig. 9. Posterior region of male with copulatory bursa fully ex- 

 truded. 



of the cap. With the final loss of the cap, probably due 

 to the movements of the parasite, it is readily believable 

 that the spines might adhere more firmly to the cap in 

 which they are embedded than to the cuticula where they 

 had their origin and thereby become lost. If copulation 

 occurs more than a single time each successive deposi- 

 tion and removal of a copulatory cap would reduce the 

 number of genital spines until in the older females no 

 spines would remain. In such an instance sexual di- 

 morphism would result from mutilation of the body of 

 one sex to render it unlike that of the other sex. 



