BULL. U. S. B. F. 1912. 



PLATE LXV. 



FIG. 25. Brook trout, showing- rectal metastasis of thyroid origin (Anal fin pinned back to show tumor.) 



FIG. 24. Brook trout, showing: large 

 round tumor springing' from the jugular pit. 



FIG. 23a. A view of normal floor of 

 mouth of adult brook trout. 



FIG. 23 Hyperemia of floor of mouth of adult brook trout, 

 so-called red floor. First macroscopic evidence of hyperplasia or 

 carcinoma of thyroid. 



