. Bulletin. Natural history; Natural history. March 1938 ROSS: NEARCTIC CADDIS FLIES 105 the clasper but also in the oedagus with its short, heavy, five-tined process, shown in fig. 6. Male.—Length mm. Head dark brown with setiferous warts and anten- nae light brown. Remainder of body. c? Genitalia Fig. 6. - Rhyacophila ynelita dark brown, with the legs and venter of the abdomen straw color. Wings uni- formly brown, the veins and stigmal region darker. General structure same as for genus, the diagnostic differences being almost entirely in the genitalia. Genitalia as in fig. 6. Seventh st
. Bulletin. Natural history; Natural history. March 1938 ROSS: NEARCTIC CADDIS FLIES 105 the clasper but also in the oedagus with its short, heavy, five-tined process, shown in fig. 6. Male.—Length mm. Head dark brown with setiferous warts and anten- nae light brown. Remainder of body. c? Genitalia Fig. 6. - Rhyacophila ynelita dark brown, with the legs and venter of the abdomen straw color. Wings uni- formly brown, the veins and stigmal region darker. General structure same as for genus, the diagnostic differences being almost entirely in the genitalia. Genitalia as in fig. 6. Seventh sternite with the small, triangular mesa! projection just above apex. Ninth segment cylindrical, onK- slightly longer dorsally than ventrally. Claspers only one-tenth longer than depth of ninth segment; the basal seg- ment has the ventral margin slighth' more than twice as long as the dorsal margin, the two being parallel; the apical segment, viewed lateralh', appears egg shaped, the dorsal side longer than the ventral side, the basal suture in- distinct dorsally, the inner margin with the dorso-basal region thickly set with long, stout setae. Tenth tergite, viewed laterally, appears short and beaklike; the dorsal aspect is divided into two halves, each one tapering toward apex and produced near meson into a short, pointed projection; the entire surface is sparsely set with setae. Oedagus as illustrated, the ventral process con- sisting of a narrow mesal style with a pair of semimembranous flaps at base; the dorsal portion is a heavily sclerotized structure with a single mesal spine at base and with the apex divided into a pair of bifid processes. Holotype, male.—Crawford County, Miclii- yan: June 16, 1935, north branch ot Au Sable River", J. \V. Leonard. Rhyacophila perda new species This species closely resembles monlana Carpenter and lobifera Betten, but differs from both in the dorsal prolonga- tion of the ninth segment which con- sequently overhangs the basal segmen
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