19483 Denning — Near ctie Trichoptera 21 
5C, with ventral bridge well marked and crossing sperma- 
theca near margin. 
Holotype. Male. — Albany County, Wyoming, Snowy 
Range Mountains, near Centennial, Wyoming, August 3, 
1947 (D. G. Denning). 
Allotype. Female. — Same data as for holotype. 
Paratypes. — 5 males, 2 females ; Woods Landing, Wyo- 
ming, August 10, 1947 (D. G. Denning). 3 males ; Poudre 
River, 15 miles west of Teds Place, Colorado, August 17, 
1947 (D. G. Denning). 3 males, 4 females ; Poudre River, 
approximately 15 miles east of Cameron Pass, Colorado, 
August 19, 1947 (D. G. Denning) . 10 males ; Rocky Moun- 
tain National Park, Colorado, August 9, 1947 (D. G. 
Denning). 
In all instances the species was collected only from 
clear, swift flowing mountain streams. 
Lepidostoma ormea Ross 
This recently described species was previously known 
only from a male collected in Utah. 
Colorado: Illinois River, south of Walden; August 10, 
1947 (D. G. Denning), 1 male. 
Collected from a shallow, clear swift flowing stream at 
approximately 8,000 feet elevation. 
Rhyacophila mirus n. sp. 
This species is very closely related to alberta Banks. 
Male. — Length 11-12 mm. Color brownish yellow, 
with a scattering of dark brown markings over most of 
forewing. First and second pair of legs light brown ex- 
cept for a light yellowish color over apical portion of tibia, 
third pair of legs luteous. Sternum of sixth and seventh 
segment with a short acute mesal projection. 
Genitalia as in fig. 6. Ninth segment with a wide emar- 
gination laterally resulting in the ventral half being 
greatly narrowed. Tenth tergite declivous from lateral 
view, reaching ventrad to margin of claspei*; from dorsal 
aspect, fig. 6A, slender, practically same width through- 
out, apical portion produced into a pair of thin plates, the 
inner pair (best viewed from lateral aspect) slender and 
