1903] NATURAL SCIENCES OF PHILADELPHIA. 591 



comparatively narrow, as in nmrtinella , but it receives the recurrent 

 nervure far beyond its middle (at its middle in viartinella type) ; in 

 size it nearly agrees with martinella; the first joint of the flagellum is 

 not much shorter than the second, seen from the front, whereas in 

 7nartindla type it is considerably shorter. 



All these insects are very easily separated from A'', americana by 

 the clear red antennae and thorax without a black stripe. At a glance 

 they look like N. ultima taraxacella, but they are Centrias, with strongly 

 punctured abdomen and spines on front coxse. They have not the 

 black diamond on the metathorax, which is seen in taraxacella. 

 Nomada scitiformis, sp. n. 



d^. — Length about 9 mm.; black with yellow markings; legs red 

 and black. Flagellum constructed and colored as in A' . scita, of which 

 I had supposed this a variety, until I saw the real scifa from Colorado. 

 N. scitiformis differs from scita thus: Somewhat larger; clypeus low, 

 no supraclypeal mark, and lateral marks shorter, so that the black area 

 below the antennae is much larger; postscutellum entirely black; ab- 

 dominal bands lemon-yellow; first segment with no band, but only a 

 spot on each side; band on second segment very broad at sides, rapidly 

 narrowing mesad, where it is interrupted; legs a darker duller red, 

 with more black; hind femora mostly black. 



Hab. — Corvallis, Ore., June 2 to 8 (Cordley). Sometimes the clypeus 

 has only the anterior margin yellow; and sometimes the first abdominal 

 segment has an interrupted band, while that on the second is narrowly 

 continuous in the middle. Five specimens examined. 



N. scitiformis and also N. scita belong to Centrias, having a spine on 

 the anterior coxa. The anterior legs of the males of these and N. 

 americana differ thus: 



N. scitiformis: Spine black, fairly long; red of leg fairly bright. 



N. scita: Spine pale red, slender and rather long, directed caudad; 

 red of leg bright. 



N. americana: Spine red, short; red of leg not s6 bright. 



Aside from these characters, the males of Centrias {-{-Nomaclula) 

 are easily separated thus: 



1. Hind femora distinctly arcuate; base of abdomen with much red, 



americana, Kirby. 

 Hind femora not arcuate; base of abdomen not red. .... 2. 



2. Antenna without a pale annulus (middle region of flagellum), 



erigeronis, Rob. 

 Antenna with a pale aimulus 3. 



3. Hind femora with much black; no supraclypeal mark, 



scitiformis, Ckll. 

 Hind femora bright red; a supraclypeal mark, . . scita, Cress, 



