130 University of Washington Publications in Biology [Vol.2. 



ARTIFICIAL KEYS TO THE GENERA AND SPECIES OF FISH IN 



WASHINGTON, OREGON AND IN CLOSELY 



ADJOINING REGIONS 



Family 1. Eptatretidae. Hagfishes or Borers 



la. Head to first gill opening 6.5 times in total length ; gill openings, ventral 

 fold and anal not bordered by white. Range : Alaska to Santa Barbara 

 Islands. Marine. Common. 

 Black Hagfish 1. Polistotrema dcani Evermann and Goldsborough 



lb. Head to first gill opening 4.5 times in total length ; gill openings bordered 

 by white ring. Range : British Columbia to San Diego. Marine. Common. 

 Common Hagfish 2. Polistotrema stoutii (Lockington) 



Family 2. Petromyzonidae. Lampreys 



la. Teeth of the buccal funnel not in distinct radiating series, but in several 

 groups ; several enlarged lateral teeth, usually multicuspid, at the edge of 

 the oral opening ; a marginal series around edge of disk ; few to many teeth 

 on the anterior part of the disk; supraoral broad, the main cusps are sep- 

 arated by a bridge. Fig. 1. 



2a. A posterior series of small teeth developed, parallel to the marginal series 

 and connecting the last pair of enlarged laterals ; 57 to 74 mytomes be- 

 tween last gill slit and anus. Range: Unalaska to southern California. 

 Marine and freshwater. Common. 



Three-toothed Lamprey. Pacific Lamprey... 3. Entosphenus tridentatus 



(Gairdner) 



2b. No teeth other than the marginals on the posterior field of the disk ; 3 

 enlarged laterals ; myotomes between last gill opening and vent 57 to 70. 



3a. Dorsal fins usually well separated by an interspace except during 

 spawning; myotomes between the last gill opening and the vent 63 to 

 70 ; all teeth sharp and strong. Parasitic. Range : Eurasia and western 

 North America. Freshwater. Locally abundant. 

 River Lamprey. Lake Lamprey. .. .4. Lampctra fluviatilis (Linnaeus) 



3b. Dorsal fins separated only by a notch to base ; myotomes between last 

 gill opening and vent 57 to 66 ; all teeth weak and blunt, non-functional. 

 Non-parasitic. Range : Eurasia and western North America. Fresh- 

 water. Common. 

 Brook Lamprey 5. Lampetra planeri (Bloch) 



Family 3. Hexanchidae. Cow Sharks 



la. Gill openings 7 on each side. Range : Puget Sound to Monterey Bay. 

 Marine. Not rare. 

 Spotted Cow Shark. Mud Shark 6. Notorynchns maculatus Ayres 



lb. Gill openings 6 on each side. Range : Mediterranean, North Atlantic and 

 North Pacific, Puget Sound to Monterey Bay. Marine. Not rare. 



Mud Shark. Shovelnose Shark 7. Hexanchus griseus (Bonnaterre) 



(=H. corinus Jordan and Gilbert) 



