292 FISHES OF ILLINOIS 



protractile maxillary, which is joined for most of its length to the skin of the 

 front of the preorbital; no teeth on vomer or palatines; no enlarged ventral 

 plates; vertebrae 42 (19+23); pyloric caeca 4; coloration largely green. 

 Size moderate, 3 to 5 inches; a single species. 



DIPLESION BLENNIOIDES (Eafinesque) 



GREEN-SIDED DARTER 



(Map LXXXIX) 



Rafinesque, 1819, Journ. de Physique, 419 (Etheostoma [Diplesion]). 

 J. & G., 497; M. V., 125 (Etheostoma); B., I, 100; J. & E., I, 1053; N., 35 (Etheos- 

 toma); J., 40; F., 66; L., 27. 



Length 3 inches; body elongate, neither cylindrical nor (technically) 

 compressed, but narrowed dorsally in front so that a cross-section of the body 

 is roughly triangular; back somewhat elevated in adults and profile very 

 convex; ventral outline straight or slightly concave; depth 5.3 to 6.3; greatest 

 width of body about ^^ its greatest depth; depth caudal peduncle 2.6 to 

 3.2 in its length. Color of upper parts light olivaceous, paler beneath, the 

 belly a light creamy white; sides marked with 5 to 8 vertical bars of rich 

 dark grassy green color, these continuous with dark saddle-hke back blotches ;* 

 below lateral line a row of Y-shaped blotches, sometimes connected so as to 

 form an irregular wavy or zigzag band of rich green; 20 to 50 small rufous- 

 orange spots scattered along sides in irregular zigzag lines, each spot occupy- 

 ing the center of a scale; head dark olive-green, mottled with darker green, 

 a dark green band passing from the eye downward and forward around 

 the upper jaw and a similar one downward to a short distance behind the 

 angle of the mouth; suborbital bar of one side usually extending beneath 

 chin to meet the bar of the other side; cheeks yellowish green, opercles dark 

 green; head pale beneath; pupil black, iris with some gold; spinous dorsal 

 with a band of rufous-orange spots at its base occupying about lower third 

 of fin, which is tipped at outer margin with a narrow edge of pale blue; second 

 dorsal with row of orange spots fainter, and without outer blue edging; other 

 fins paler, greenish; females with orange spots at base of spinous dorsal less 

 brilliant, and with these spots missing on second dorsal. Head short, irregu- 

 larly pyramidal, flat and broad below, 4 to 4.6 in length; width of head 1.5 

 to 1.9; interorbital space narrow, flat, 5.2 to 6.8 in head; eye roundish, high, 

 and somewhat protruding, 3.1 to 3.6; nose 3.1 to 3.7, the muzzle much 

 decurved and projecting beyond the inferior mouth; mouth small, inferior, 

 horizontal, maxillary reaching to front of orbit, cleft 3.1 to 3.6 in head; 

 lower jaw much shorter than upper; lips rather more prominent than is 

 usual in darters; gill-membranes connected broadly across isthmus, the 

 distance from tip of snout to free posterior margin of membranes being 

 IK to IM greater than to back of orbit. Dorsal fin XIII-XIV, 13-14; 

 spinous and soft portions joined or but slightly separated; height of first 

 dorsal 1.6 to 2.3 in head, second 1.4 to 1.6 (height of first 68 to 90 per cent, 

 of second); caudal slightly emarginate; anal II, 8 or 9; pectorals .8 to .9 in 

 head; ventral spines and first 4 or 5 rays rather fleshy and often somewhat 



* These blotches are the only part of the bars usually visible in preserved specimens, show- 

 ing in life as dark pigmented areas under the green of the bars. 



