280 
[November 
On the North American species of the genus NOMAD A. 
BY E. T. CRESSON. 
Gen. NOMADA, Fabr. 
The characters of this genus are given by Mr. Smith, (Bees of 
Great Britain, p. 116), as follows :— 
£od;y destitute of pollinigerous appendages. Jlead transverse, as wide as the 
thorax. Antennce geniculated, filiform, nearly as long as the thorax. Lahrum 
transverse, its anterior margin rounded. Mandibles bidentate, in the males 
simple, and rounded at their apex. Mentum slightly narrowed at the base, the 
labium of the same length as the mentum, broad and narrowed a little before 
the apex, whieh is rounded. Labium grooved and transversely striated. Para- 
glossce about one-fourth the length of the labium. Labial palpi four-jointed, 
continuous, a little shorter than the labium, the basal joint longer than the 
three following, the second about one-fifth of the length of the basal joint, the 
two following each shorter than the preceding. Maxillary palpi 
nearly as long as the apical lobe: the basal joint minute, the second and third 
joints of about equal length, the remaider gradually decreasing in length, and 
each more slender than the pi*eceding. Superior wings have one marginal and 
three submarginal cells, the second submarginal receiving the first, and the 
third the second recurrent nervure. Legs simple in both sexes. Abdomen: the 
apical segment truncate at the apex in the females, acute in the males. 
The beautiful bees constituting this genus are parasitic, principally, 
on those of the genera Andrena and Halictus. Very little is known of 
their economy. They are mostly gayly colored, resembling in this re¬ 
spect some of our wasps. Most all the specimens that I have exam¬ 
ined, have a longitudinal carina, more or less developed, between the 
antennae; the scutellum is mostly subbilobate, only in one specimen 
bilobate; the “tubercles’’ mentioned in the descriptions are two hard, 
round, shining elevations, one on each side of the thorax, before and a 
little below the base of the wings; the wings are generally clouded 
especially about their apical margins, with a more or less hyaline, lunu- 
lar spot near the tip; the stigma is often lighter colored than the rest 
of the nervures; the shape of the second and third submarginal cells 
varies very much, even in the same species; I have before me a 9 spe¬ 
cimen from Maine (iV. ohliterata n. sp.), which has the second trans¬ 
verse cubital nervure in both superior wings entirely obliterated, 
thereby throwing the second submarginal cell into the first, and mak¬ 
ing the latter as long as the marginal. In another 9 specimen from 
Kansas (iV. luteola var ?) we have the normal neuration on the left 
