DESCRIPTION OF FIGURES 16 TO 19 

 Thyroid "tumors" in the shark sucker, Echeneis naucrates. 



Pic. 16 — GroM appcanncc of a tumor protruding through Fic. 18. — Microscopic appearance of tumor shown in Fig. 



the floor of the mouth The top of the head has b?en re- 16. Many of the acini are very small, with only a tiny 



moved b>- a acction which passed through the level of the lumen lined by tall columnar cells. As the acini increase in 



cjrca (vbibk \n the photograph as bilateral heavy black size the lining epithelial cells become flattened, and the 



Cfwcwii). amount of colloid increases. There are many marginal vac- 



Fic. 17.— Thyroid tissue bet wren the bony lamellae of a uolcs in the colloid. Mag. X 70. 



branchial arch. On the left is normal epidermis. This ap- Fk;. 19.— Gross appearance of a tumor on the floor of the 



parrnlt> aberrant location of thyroid timae is normal for mouth in the living fish. 

 tekott 6sbes. Mag. X 100. 



722 



