NOTKOPIS 



135 



dusky above, the dark punctulations on the scales confined mostly to the 

 edges; sides leaden silvery, with a black stripe extending forward through 

 eye to end of snout; belly with an orange tint; fins plain. Head small, conic, 

 3.9 to 4.2 in length; width of head 1.8 to 2 in its length; interorbital space 

 2.6 to 3.1; eye quite large, 2.7 to 3 in head, being usually about ^ longer 

 than the snout, the distance from the tip df which to the anterior rim of the 

 pupil is about equal to the diameter of the orbit; nose short and rather 

 sharp, 3.5 to 3.8 in head; mouth moderate, oblique, the upper lip as a rule 

 on a level with the upper margin of the pupil; cleft of mouth making an angle 

 of 40 to 60 with the vertical; maxillary scarcely reaching front of orbit, its 

 length about % the diameter of the very large eye; jaws subequal, the isthmus 

 less than pupil. Teeth as a rule 1, 4-4, 1, in occasional instances 1, 4-4, 0, 

 0, 4-4, 1, or 4-4; the first three teeth of the outer row usually strongly hooked 

 and with a well-developed groove whose edges are somewhat crenate; intes- 

 tine shorter than body and head; peritoneum silvery. Dorsal fin with 8 

 rays, slightly nearer snout than base of caudal, set almost directly over 

 ventrals; longest dorsal ray somewhat less than head (1.1); anal rays 8, 

 occasionally 7; pectorals short, less than % to ventrals, 1.3 to 1.6 in head; 

 ventrals reaching vent. Scales 5, 35-38, 3; 12 to 14 scales before dorsal; 

 lateral line as a rule developed only anteriorly; some specimens met with, 

 however, in which not more than 2 or 3 pores were lacking on posterior 

 half of body. 



FIG. 30 



The typical form of this species appears to be confined, with 

 us, f to the northern part of Illinois, being most abundant in the 

 small glacial lakes of Lake and McHenry counties, where it is 

 found in clear, cool water among weeds and over sand along 

 shore. Specimens taken from the headwaters of the Fox, Des 

 Plaines, and Du Page rivers, and some from the upper Rock 

 and its tributaries (Yellow creek, Stephenson county, Kiswaukee 

 River at Sycamore, Rock River at Oregon, and Green River at 

 Geneseo) have the teeth 0,4-4, 1, or 1. 4-4, 1, though the body 

 is somewhat slender and the eye is hardly so large as in the lake 

 form. From farther southward we have about 80 collections, 

 chiefly from the sluggish waters of the Illinois River and tribu- 

 tary lakes at Havana and Meredosia, in which the dentition is 



