Bull. U. S. B. F., iyi<>-2o. 



I'LATn; X\^ 



Fig. 3. — Three pill filaments of rock bass, \vith jiJochidia of 

 mucket. 



i'u;. 2. — Part of fig. i. enlarged. 



Fig. 4— Stages in formation of cyst surrounding a yluchidium of the mucket. Taken at 1 - minutes, 30 minutes, i Inmr, 



and 3 hours, respectively, after infection. 



«i^ 



^. 



v^JS! 



Fii-,. 5, Young nuukcts, one week after liberation from the fish, showing new 

 growth of shell, cilia on foot, and positions assumed in crawling. Enlarged. 



[Figs. 1-5 after I,cfevrc and Curtis., 



Fig. 6. — Voimg Lake i'epiu muckcts at 

 ages of 1, 2. 3. and 4 months, respec- 

 tively. Xatural size. 



