NOTKOPIS 155 



deeper and more compressed body, and from the latter by the smaller scales, 

 which are much crowded anteriorly. Length 3 inches; body as a rule rather 

 deep and compressed, the depth 3.2 to 4.2 in length; profile usually angled 

 at nape in adults; caudal peduncle less than head, its depth 1.7 to 2.4 in its 

 length. Color dark purplish blue above, greenish blue, not silvery, on middle 

 part of sides, and greenish lower down and on belly; a dusky lateral band on 

 caudal peduncle, becoming obsolete forward; scales, except on belly, dusted 

 with dark specks but not prominently dark-edged; dorsal fin with a more or 

 less prominent black spot at its base in front*; anal tipped with dusky in 

 males; dorsal with or without a dusky bar mesially; spring males with the 

 dorsal and caudal fins greenish at base and bright brick- to blood-red out- 

 ward; lower fins nearly uniform red, the pectorals less brilliant, pinlcish or 

 rose; females pale olive, plain. Head conic, comparatively pointed, 4 to 

 4.1 in length; width of head 1.8 to 2.1; interorbital space quite convex, 2.2 

 to 3 in head; eye small, shorter than snout, 3.4 to 4.2 in head; nose 2.8 to 3.3; 

 mouth moderate, oblique, tip of upper lip above lower margin of pupil; 

 maxillary 2.7 to 3.2 in head, reaching front of orbit; jaws about equal; isthmus 

 less than pupil. Teeth 2, 4-4, 2, with more or less developed grinding sur- 

 faces on the median teeth of the outer row, this surface narrow and either 

 plane or concave; intestine .8 to .9 of length of head and body; peritoneum 

 silvery, rather sparsely and coarsely specked with brown. Dorsal rays 8, 

 the fin set well back of ventrals; longest dorsal ray 1 to 1.1 in head; anal 

 rays 10, 11, or 12, usually 11; pectorals more than % to ventrals; ventrals 

 to or past vent. Scales 9 or 10, 41 to 48, 4, crowded anteriorly, the rows 

 in front of dorsal fin 26 to 30, lateral line deeply decurved. 



This is an exceedingly handsome species, especially during 

 the breeding season. It is commonly said to be most frequently 

 seen in clear, swift streams. Our frequency coefficient for 

 creeks reaches, in fact, the extraordinary^ number of 3.9, while 

 that for the smaller rivers is 1.9, and for the larger rivers, .16. 

 In lowland lakes we have found it but once in 549 collections, 

 and in glacial lakes not at all. On the other hand, 109 collections 

 for which we have the necessary data give us a frequency 

 coefficient of 1.76 for still-water situations as compared with 

 those with a rapid current — from which we may infer that in 

 lUinois, at any rate, the species is more frequently to be found 

 in quiet waters than in those wuth a rapid flow. Our similar 

 data concerning cleanness or muddiness of bottom, drawn from 

 69 collections only, give us no evidence of any definite choice, 

 the corresponding coefficient being 1.01. The species has been 



* Great variation in color is found in our specimens, making it extremely difficult to dis- 

 tinguish varieties. We have included all Illinois specimens accordingly under the oldest name 

 for this portion of the range of this wide-spread and variable species. Most of our specimens 

 have the dark blotch at base of dorsal prominent and anal dusky in males (airipes); others, but 

 much fewer in number, have the spot faint or obsolete {macrohjiidotus) ; in some specimens there 

 are distinct traces of 3 to 5 vertical bars of dusky on back portion of sides and fore part of caudal 

 peduncle {fascioJaris';) . 



