208 Mr. T. D. A. Cockerell on 
hind femora behind are conspicuously blackened; hair on 
inner side of basal joint of hind tarsi pale golden ; a trilobed 
black mark at base of first abdominal segment. 
Hab. Corvallis, Oregon, May 24. 
Received from Mr. Viereck. 
Mr. Viereck has called my attention to a character of the 
venation which is useful for separating closely similar species 
of Nomada. Applied to the species above described it gives 
these results :— 
(1) Transverso-medial nervure joining discoidal 
nervure some distance from its base*...... N. Clarki, N. Grayt, 
NV. oregonica. 
(2) Transverso-medial nervure joining discoidal 
neryure very near to or at its base ......., N. Lewisi, N. Astori, 
NV. corvallisensis, N. 
ultima, N. erythro- 
chroa, N. Fowlert. 
Nomada aquilarum, sp. n. 
$ —Length hardly 6 millim. 
Black, with cream-coloured markings; abdomen broad 
and quite small. Facial quadrangle square, the orbits 
parallel ; eyes pale grey; anterior half of clypeus, triangular 
lateral marks short and blunt above, and broad base of man- 
dibles cream-colour; mandibles simple; labrum dark, very 
densely punctured ; antenne dark brown above, ferruginous 
beneath; third jointa little longer than fourth, paler and less 
shining than rest of flagellum ; cheeks wholly black; meso- 
thorax extremely densely punctured; the cream-coloured 
tubercles offer the only light marking on thorax; scutellum 
hardly bilobed; tegule testaceous, with a small cream- 
coloured spot. Wings irregularly stained with brown ; ner- 
vures dark; transverso-medial nervure joining discoidal at 
its base. Legs black, anterior femora and tibiz in front and 
anterior tarsi pale ferruginous; middle and hind tibiz at 
base, spot near apex of middle tibie, and large wedge-shaped 
mark on apical portion of hind tibiz cream-colour; hair on 
inner side of basal joint of hind tarsi very pale golden. Abdo- 
men with shallow punctures ; first segment black, second to 
fourth with a large wedge-shaped cream-coloured mark on 
each side, fifth and sixth with bands; posterior margins of 
third and following segments reddish ; apical plate not at all 
# This is true also of the following species in the Cresson collection, as 
reported by Mr. Viereck :—W. grandis, superba, Edwardsit, affabilis, jocu- 
laris, Morrisoni, civilis, electa, bella, lepida, vincta, vicinalis, bisignata, 
maculata, perplexa, pygmea, melhiventris, 
