282 FISHES OF ILLINOIS 



PERCINA CAPRODES (Rafixesque) 



LOG-PERCH 

 (Map LXXXV) 



Rafincsque, 1818, Amer. Month. Mag., 534 (Scisena). 



J. & G.. 499; M. V., 126; B., I, 57; .J. & E., 1026; N., 36; J., 39; F., 65; F. P., I. 

 3, 25; L.. 26. 



The largest of our darters, length 4 to 6 inches; body cylindrical, elongate; 

 depth 5.4 to 7 in length; greatest width of body about Yz of its greatest 

 depth; depth of caudal peduncle 2.6 to 2.9 in its length. Color olive-buff to 

 yellowish; sides of adults crossed by from 30 to 40 bars of dark green color, 

 varying* in width and in extent from above downward, the most usual 

 arrangement being an alternation of short and narrow with wider and longer 

 ones, the merging of bars producing in some older specimens a more or less 

 reticulated pattern on the sides and forming on the back 3 or 4 large saddle- 

 like l:)lotches; fewer bars (15 to 30) in j'ounger specimens, the intermediate 

 narrower and shorter ones being faint or entirely absent in the very young; 

 a small but prominent black spot at base of caudal fin, encircled by a bancl 

 of yellow; snout dusky; cheeks with iridescent green, blue, and yellow; iris 

 with golden margin; dorsal and caudal fins barred, other fins plain. Head 

 3.9 to 4.3 in length, long and pointed; width of head 1.9 to 2.2; interorbital 

 space flat or slightly concave, 4 to 4.8 in head; eye high, obliquely set, its 

 long diameter 3.6 to 4.2 in head; snout long, conic, with a pad at its tip, 2.8 

 to 3.3 in head; mouth small, inferior, overhung by the pig-like snout, max- 

 illar}' reaching scarcely to posterior nostril-opening; cleft 3.4 to 4 in head; 

 lower jaw much shorter than upper; gill-membranes narrowly connected, 

 distance from tip of snout to their angle scarcely greater than to back of 

 orbit. Dorsal fin XII-15; spinous and soft portions usually very little sepa- 

 rated, or not at all; height of first dorsal 2 to 2.3 in head, of second 1.6 to 2.2 

 (height of first 74 to 94 per cent, of second); caudal truncate; anal II, 10-11 

 pectorals 1.2 to 1 .4 in head; separation of ventrals about equal to their width 

 at base. Scales 9-11, 83-93, 12-14; lateral line usually complete, as many 

 as 1 to 6 pores occasionally lacking; cheeks and opercles fully scaled; nape 

 of typical specimens fully scaledf; l)reast naked; belly with deeply embedded 

 scales and a median row of rather small pectinate caducous plates. 



Sexual differences not marked. The majority of our specimens are 

 young, and no gravid females appear among them. Testes were large and 

 white in males taken on the 12th of June 1901. 



The darter is distributed through the state from Cairo 

 to South Chicago and the northeastern glacial lakes, mainly, 

 however, in the larger streams. We have found it relatiA^lj^ 

 most abundant in medium-sized rivers, and next so in creeks, 

 its frequencj' coefficients for such streams, as represented hy our 



* For an interesting paper on variation in the color pattern of this species see \Y. .1. Moenk- 

 haus, Amer. Nat., Vol. 28, pp. 641-660. 



t Naked in var. zehra Agassiz (Jordan and Evermann, Bull. U. S. Nat. Mus., No. 47, I., 

 p. 1027). Some apparent specimens of that form were taken in Illinois in early collections by 

 the senior author. 



