Lygeide. 109 
tends to impede the development of black. This, I feel 
little doubt, is the explanation of the red-bodied forms of 
Andrena in the Hymenoptera, occurring more commonly 
in hot dry summers than in cold damp ones; and in the 
genus now under consideration, one species at least, 
S. neglectus, varies in the amount of black on the second 
antennal joint. I have specimens with a broad black band 
at the apex, others witha very narrow one ; and why others 
should not occur without a band at all I fail to see. On the 
form of the styles in the ¢ I place great value, but I can 
only detect differences between three of the forms of style 
Ihave examined, and the differences which exist between 
these appear to me to be traceable to modifications of a 
common form; at the same time, they are distinct enough 
for practical use, and therefore should not be put aside. 
Grouping them by the form of the styles, I should unite 
afinis and grandis; puberulus and neglectus ; decoratus 
remaining distinct; of pictus the style has not been ex- 
amined, The characters of the form of the pronotum 
and membrane seem to me most unreliable, as both these 
vary in form correlatively with the development of the 
wings ; and to be certain that a pronotal difference be- 
tween any two of these insects is reliable, one must be 
certain that the wings are equally developed in both, a 
position very hard to obtain. As an instance of variability 
of the length of the membrane in the brachypterous form, 
I may mention that Ihave one example of puberulus, Horv., 
in which the membrane projects beyond the apex of the 
corium by about half its diameter, and I have another, in 
which it hardly projects beyond the apex of the corium at 
all, and yet both were taken in the same batch, and are 
clearly identical. After very careful consideration, I feel 
no doubt that all the so-called species are races of one, 
still they are recognizable as a rule, and therefore I give 
them ; other characters may yet present themselves to dis- 
tinguish them apart more satisfactorily. 
