PLATE V. 



Fig. 1. Corethra appendiculata, head of larva. 



Fig. 2. '* " portion of heart with its muscles, 



a. chitinous projection of the body wall to which are at- 

 tached two muscular threads; b. peripheral muscle; c. 

 proximal muscle attached to the wall of the heart; d. 

 muscles scattered over the surface of the heart, serving 

 as contractors; e. venous opening. 



Fig. 3. do., extremity of body. 



Fig. 4. do, abdomen of the pupa. 



Figs. 5, 6, 7. Rotifera found with entomostraca in Minnesota. 



Fig. 8. Flask-shaped rotifer, hermaphrodite, with eggs and sperm, 

 a. jaws and head; b. shell gland; c. glandular portion of 

 the stomach; d. testes; e. oesophagus; f. one of several 

 embryos. 



Fig. 9. jaws of the above. 



Fig. 10. similar animal, female, deadly enemy to Chydorus. 



Fig. 1 1 . jaws of same. 



Figs. 12, 13. ? pedicularis, ecto-parasite of Diaptomus. 



