NOTROPIS 155 



bv the 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 ped- 

 uncle, 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 l3ase and bright brick- to blood-red 

 outward; lower fins nearly uniform red, the pectorals less brilliant, pink- 

 ish 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 con- 

 vex, 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 surfaces 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 coefBcient of 1.76 for still- 

 water situations as compared with those with a rapid current — from 

 which we may infer that in Illinois, at any rate, the species is more 

 frequently to be found in quiet waters than in those with a rapid 

 flow. Our similar data concerning cleanness or muddiness of bot- 



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

 to distinguish 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 prom- 

 inent, and anal dusky in males (atripes); others, but much fewer in number, 

 have the spot faint or obsolete (•ynacrolepidoius) ; in some specimens there are dis- 

 tinct traces of 3 to 5 vertical bars of dusky on back portion of sides and fore part 

 of caudal peduncle {fasciolarisi) . 



