127(5 
PERNAMBIS; ACOSSUS; PRIONOXYSTUS. By H. G. Dyar t- 
inlrusa. 
manfredi. 
henrici. 
intervcnala. 
fuscescens. 
albescens. 
undosus. 
c.entercnsis. 
populi. 
generosus. 
angrezi. 
ore. 
H. hitrusa B. d- Benj. is so very closely allied to bertholdi that it is only comparatively to be separated. 
It is somewhat larger, with a stronger body, the dark dusting between the median branches more distinct, 
brownish, forming a dark roundish spot between 2 and 3. Hindwing brown. Expanse of wings: 37—47 mm. 
South California. The larva lives in the trunk and roots of Lupinae. 
H. manfredi Neum. (182 a) is the smallest and lightest species. Body and forewing including fringe 
yellowish white, with tiny light brownish speckles and a discal blotch of the same colour. Hindwing mono¬ 
tonous, somewhat darker. Expanse of wings: 30 mm. Arizona. 
H. henrici Grt. (182 a) is as large as bertholdi which it also resembles somewhat, though it is more inter¬ 
rupted by white, the costal margin broadly silvery white like the median vein, too, the rest of the wing brownish, 
slightly dusted over with ochre. Hindwing dark blackish brown in the $, lighter in the Arizona. 
14. Genus: Feruambis Schs. 
Forewing without the areole, the discal vein with a long fork, the veins 1 and lb separated; vein 2—11 
from the cell. 4 and 5 arising together, 6 and 7 on a short stalk. Discal vein of hindwing forked, veins 3 -f- T 
together from the sharp lower cell-angle, the cell itself angularly bent inward; (5 and 7 separated with an oblique 
connecting bar far outside; 8 free. Antennae of $ bipectinate, of $ flattened laminate. 
Type: P. intervenata Schs. 
P. intervenata Schs. (183 d). Forewing dark mouse-coloured grey, all the veins broadly striped white. 
Described from a single $ which is much damaged. Brazil (Pernambuco). 
P. fuscescens Dgn. (183 d). Forewing dark mouse-coloured brown, all the veins narrowly striped white, 
only the median vein somewhat more broadly striped. According to a single $ from Argentina. 
P. albescens Dgn. (183 d). Forewing grey, all the veins broadly striped white, subcostally flown together 
and forming a broader stripe. Hindwing white with grey internerval spots at the margin. Only 2 $5 known, 
one from Venezuela, the habitat of the type not known. 
15. Genus : Acossus Dyar. 
Veins l and 11) of forewing separated, discal vein forked on both wings, areole narrow, projecting beyond 
the discal cell, 7 —9 from the apex, 10 before it and 11 more remote from the discal cell. Cell of hindwing 
entering with a flat angle; 6 and 7 stalked; the upper edge of the cell projecting angularly with a bar to vein 8. 
Type: A. undosus Lint. 
A. undosus Lint. ( = brucei French ) (182 b). Collar ochreous, thorax grey; the white ground of the 
forewing finely transversely striated black with 2 thicker lines through the middle and before the distal margin. 
Abdomen and hindwing light grey, the latter less striated. Colorado; Wyoming. Larva probably in poplars. 
A. centerensis Lint. (182 b) is well distinguished by the very scantily scaled hindwings with black fringes 
and a blackish-haired basal part of the inner margin. Distal part of forewing likewise more scantily scaled, 
the basal part more densely scaled black, everywhere finely transversely striated, often connected into fine 
lines. Northern States, to the west as far as British Columbia. The larva lives in poplars. 
A. populi Wlcr. (182 b) differs from undosus in the absence of the thicker transverse lines; forewing 
very light ash-grey, very finely transversely striated and reticulated. Hindwing even much lighter and scarcely 
striated. North-Western North America. - generosus Dyar is more or less shaded black, a much darker form 
from the Northern Rocky Mountains. - angrezi Bailey is another form, perhaps also a distinct species, with 
a black thorax and yellowish grey collar, the forewing more irregularly shaded black, for instance in the apical 
and marginal thirds, inwardly widened obliquely downward, with longer internerval streaks before the margin. 
Hindwing yellowish grey. Nevada. — ore St hr. (182 b) which many consider to be a distinct species, is again 
a lighter form, but not so light as populi and densely and irregularly mixed with dark. Colorado. The larva 
lives in poplars. 
16. Genus: Prionoxystus 
Sexes dissimilar; antennae pectinate in both sexes. Thorax covered with flat scales. Distal margin of 
hindwing concave in the d, rounded in the $. Neuration as in Acossus. 
Type: P. robiniae Peck. 
