MAXILLARY 

 HEAD OF VOMER 

 -PALATINE — 



SHAFT OF VOMER 



MANDIBLE 

 TONGUE 



HYOID BONE 

 GILL ARCH 



'^ B 



Figure 3. — Location of dentition in (A) the roof and (B) tlie floor of the mouth of salmonid fishes. (Presence or 

 absence of teeth on the vomer or tongue may be determined by use of the little finger or a blunt instrument. The 

 small hyoid teeth at the base of the tongue are located between the gill arches of the lower jaw and are difficult 

 to find.) 



6. (18) Dorsal fin with large dark spots. 



Trout 

 Genus Salmo 



7. (53) Adipose fin not orange; no row of 



pale round spots along lateral line. 



8. (12) * Small hyoid teeth at base of tongue. 



(Fig. 3B) 



9. (13) Not more than five parr marks on 



mid-dorsal ahead of dorsal fin. 



10. (14) Maxillary reaching past posterior 



margin of eye. 



11. (15) Red or yellowish hyoid mark under 



lower jaw. Tail usually black spotted. 

 Cutthroat trout 

 10 9 6 (Salmo clarki) 



2 4 



12. (8) *No teeth at base of tongue. 



13. (9) Five to 10 parr marks along mid-dor- 



sal ridge ahead of dorsal fin. 



14. (10) Maxillary short, not reaching past 



posterior margin of eye. 



15. (11) No hyoid mark under lower jaw. Few 



or no spots on tail. 



IG. (20) Parr marks almost round. 



Rainbow or 



steelhead trout 

 (Salmo gairdneri) 



'3 - 6 ,6 



17. (4) Anal fin longer than high, with 13 



or more developed rays. (Fig. 2B) 



18. (6) Dorsal fin without large dark spots, 



may be black tipped. 



Pacific salmon 

 Genus Oncorhynchus 



19. (20) No i)arr marks. Fry leave fresh 



water while small — approximately 

 1.75 inches (45 mm) long. 



Pink salmon 

 (0. gorhuscha) 



