. Bulletin. Natural history; Natural history. M4 Illinois Natlral History Survi-y Kullhtin lol. 22. Art. 2. Fig. 111.—Nymph of I so perl a bnrksi. except tenth ; posterior margin of each ter- gite with numerous short, stout, pale setae; some scattered short, stout setae together with fine hairs on central area of tergites. Cerci long, many segmented, segments progressively longer from base to ; a longitudinal row of long fine setae on dorsal surface of apical segments in addition to smaller spinelike ones encir- cling apex of each segment. Approximately mature specimens with body length o
. Bulletin. Natural history; Natural history. M4 Illinois Natlral History Survi-y Kullhtin lol. 22. Art. 2. Fig. 111.—Nymph of I so perl a bnrksi. except tenth ; posterior margin of each ter- gite with numerous short, stout, pale setae; some scattered short, stout setae together with fine hairs on central area of tergites. Cerci long, many segmented, segments progressively longer from base to ; a longitudinal row of long fine setae on dorsal surface of apical segments in addition to smaller spinelike ones encir- cling apex of each segment. Approximately mature specimens with body length of 11 mm. No thoracic, anal or submental gills. Nymphal and exuvial records are as fol- lows. Illinois.—Herod, Gibbons Creek: April 19, 1937. H. H. Ross & C. O. Mohr, 1 nvmph. Golcosda: May 13, 1939, B. D. Burks & G. T. Riegel, 1 exuvia. Eddvville, Lusk Creek, Pope County: April 30, 1940, 2 nymphs; May 1, 1940, 1 nymph; May 9, 1940, 2 nymphs; Mav 24 and June 1, 1940, manv exuviae; all collected by B. D. Burks k C. O. Mohr. This is another new species first found as a nymph and. because of distinctive features of nymph, recognized as new to the Illinois faunal list before adult was reared. Hearings and collection of ma- terial prove it to be a previously unde- scribed species. The combination of nymphal and adult characters separates it from all other species of Isoperla. Al- though much smaller than ventralis (Banks), it somewhat resembles this spe- cies in general color pattern of adult. In the nymph, the transverse bands on ab- dominal tergites place it with such species as marlynia Needham & Claassen (^ clio of American authors). I take pleasure in naming this species for Dr. B. D. Burks, Assistant Ento- mologist on the staf? of the Illinois Nat- ural History Survey, who has assisted with the collection and rearing of stonefly ma- terial in Illinois and elsewhere. Isoperla lata new species Male.—Basic color brownish to black. Dorsum of head with a small yell
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