1936] Schnltc: Keys to Fishes 143 



3a. Mouth inclined at an angle of about 15° ; upper profile of snout smooth 

 without conspicuous hump caused by premaxillary spines. Range : 

 Klamath Lake, Oregon. Freshwater. Common. 

 Sucker of Klamath Lake 64. Chasmistes brevirostris Cope 



3b. Mouth inclined at an angle of 40° or over. 



4a. Mouth inclined at an angle of about 40° ; head about 3.9 to 4 in body ; 

 snout 2 2 /t, to 2j4 in head ; premaxillary spines more protruding than 

 in cope'x. Range : Upper Klamath Lake, Oregon. Freshwater. Common. 

 Sucker of Upper Klamath Lake 65. Chasmistes stomias Gilbert 



4b. Mouth inclined at an angle of 45°; head 3 2 /$ in body; snout less 

 prominent, 2.5 in head; premaxillary spines less protruding than in 

 stomias. Range : Upper Klamath Lakes, Oregon. Freshwater. Com- 

 mon. 



Sucker of Upper Klamath Lake 



66. Chasmistes copci Evermann and Meek 



lb. Mouth inferior ; lips thick with many papillae. 



5a. A distinct notch at the corner of the mouth between upper &nd 

 lower lips, fig. 37 ; upper lip recurved ; lower lip but little incised, 

 3 or 4 rows of papillae crossing the mid-line; edge of jaw inside 

 the lower lip with a hard cartilaginous sheath ; scales about 16 

 +90 to 100+14; scales before dorsal about 48; fontanelle not fully 

 closed, (fig. 36) ; dorsal 10 or 11; anal 7. Range: Columbia River 

 basin and Upper Missouri. Freshwater. Common. 

 Mountain Sucker 67. Pantosteus jordani Evermann 



5b. No distinct deep notch at the corner of the mouth between upper 

 and lower lips, occasionally a very slight indentation appears on 

 a few individuals, fig. 13; upper lip not recurved but nearly flat; 

 edge of jaw inside the lower lips without a hard cartilaginous 

 sheath, the sheath if present rather flexible; fontanelle present or 

 absent. 



6a. Lower lip not very deeply incised, at least 1 or 2 rows of pa- 

 pillae are continuous across the mid-line. 



7a. Fontanelle present. Fig. 36. 



8a. Scales 20 to 22+97 to 111 + 19 to 22; scales before dorsal 

 53 to 58; dorsal rays 11 to 13 (usually 12) ; peritoneum nearly 

 jet black, the color showing through the body wall in the 

 young. Range : Columbia River in eastern Washington, Ore- 

 gon and Idaho. Freshwater. Abundant. 

 Fine-scaled Sucker of the middle and lower Columbia River 

 68. Catostomus syncheilus Hubbs and Schultz 



8b. Scales 15 to 19 + 73 to 79+14 to 15; scales before dorsal 

 37 to 42; dorsal rays 10 or 11; 2 or more rows of papillae 

 cross the mid-line of the lower lip ; peritoneum dusky, not 

 jet black. Range: Oregon Lakes and tributaries. Fresh- 

 water. Common. 



Coarse-scaled Sucker of Warner Lake Basin 



69. Catostomus warncrensis Snyder 



