1936] 



Schults: Keys to Fishes 



111 



ARTIFICIAL KEY TO THE FAMILIES OF FISHES 

 OF WASHINGTON AND OREGON 1 



la. Mouth a sucking disk, without jaws, but with teeth on the disk; a single 

 median nostril ; body eel-shaped with gill openings pore-like, 6 to 15 in 

 number on each side. Fig. 1. 



Rq.3 



Fig. 1. A diagram showing the arrangement of the teeth in the buccal cavity or 

 mouth cavity of lampreys. Dk — disk teeth; Ling — lingual teeth; Lt — lateral teeth; Info — 

 infraoral teeth; Oe — oral opening leading to the oesophagus; Pap — papillae of lips; Sp — 

 supraoral teeth. 



Fig. 2. Prionace glauca, showing the five gill openings on the side of the body, and 

 two dorsal fins without spines. Modified after Jordan and Evermann. 



Fig. 3. The lunate keeled tail of a "tiger shark." Ke — keel on caudal peduncle. 



2a. Eyes covered by skin and aborted; gill openings 10 to 15 in number on 

 each side and remote from head. 

 Hagfishes 1. Eptatretidae, p. 130 



2b. Eyes developed in adult but concealed in the larvae ; gill openings close 

 behind head and 7 in number on each side. 

 Lampreys 2. Petromyzonidae, p. 130 



lb. Mouth normal, agape, with well developed jaws; nostrils not single or me- 

 dian but paired. 



a Certain parts of this key were modified after E. C. Starks, 1921, Fish. Bull. No. 5, 

 California Fish and Game Commission. 



