Bull. U. S. B. F. 1912. 



Plate LXV. 



Fig. 25. — Brook trout, .'^howiiig rectal metastasi.s of thyroid origin (Anal fin pinned back to show tumor.) 



Fig. 24. — Brook trout, showing large 

 round tumor springing from the jugular pit. 



Fig. 23n. — A view of normal floor of 

 month 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. 



