1903.] NATURAL SCIENCES OF PHILADELPHIA. 565 



less), middle tibiae at apex, first joint of middle tarsi in front, and hind 

 tibiae at apex, yellow; abdomen closely and minutely punctured, lemon 

 yellow, the segments black at base and more or less ferruginous api- 

 call}^; first segment with the basal half black, the apical half (except 

 the hind margin) ferruginous centrall}', with a yellow patch on each 

 side; apical plate ferruginous, notched; venter l)lack at base, other- 

 wise varied with yellow and red. 



Var. a. — Somewhat smaller; no light spots at anterior corners of 

 scutellum. 



Hab. — Pasco, Washington State, May 25, 1896 (Trevor Kincaid). 

 Var. a, Los Angeles county, Cal. {Coquillett) ; in U. S. Nat. Museum. 

 The front coxae exhibit a very small spine, showing some affinity to 

 Robertson's genus Centrias; but the insect is best referred to Xan- 

 thidium, near to A^. lutcoloidcs. 

 Nomada (Xanthidium) decempunctata, sp. n. 



d^. — Length about 8 mm., rather slender, not very hairy (white hair 

 on face, cheeks and sides of thorax), black and yellow. Ej^es pale 

 green; inner orbital margin presenting a double curve; mandibles 

 except tips, labrum, clypeus, supraclypeal mark, lateral face-marks 

 (rapidly narrowing from clypeus and ending in a sharp point on orbital 

 margin at about level of antennae), stripe at top of eyes, and stripe 

 beneath eyes extending half-way up cheeks, all yellow; scape swollen, 

 but not excessively so, yellow in front, black behind ; flagellum ordinar}^, 

 dull reddish beneath, black above, last joint obtuse; third antennal 

 joint conspicuously shorter than fourth ; mesothorax extremely densely 

 punctured, nearly bare of pubescence; upper border of prothorax, 

 tubercles, narrow marginal stripe at sides of mesothorax, elongate spot 

 between tegulae and scutellum, scutellum except margins, stripe on 

 postscutellum, two round spots sublaterally on metathoracic enclosure, 

 large subquadrate patches on metathorax, somewhat diamond-shaped 

 spot behind tubercles, very large patch extending across pleura, and 

 tegulae, all lemon-yellow ; legs yellow; coxae black behind ; hind femora 

 black behind except at apex ; anterior and middle femora, and all the 

 tibia), wdth a black stripe behind, that on hind tibiae covering nearly the 

 whole surface, that on middle femora double (a broad and narrow stripe 

 running parallel) ; middle and hind tarsi mostly black behind ; wings 

 fairly clear, dusky at apex, nervures and stigma dark brown; stigma 

 large; second submarginal cell very narrow, higher than broad, receiv- 

 ing the first recurrent nervure at its middle ; first submarginal cell con- 

 siderably larger and longer than the other two combined ; third greatly 

 narrowed above; basal nervure ending well basad of the transverse- 



