126 
or dots on the apical portion and these minute and dim; the inner 
field is almost always immaculate; the posterior half of the intercalate 
vein apparent. The wings pellucid, but when living have, next the 
base, a bluish-white tinge; a larger portion of the nerves and nervules 
dark. The black stripe on the side of the pronotum nearly always 
apparent even in the darkest individuals; head and anterior lobes of 
the pronotum with the velvety appearance so marked in spretus , but 
here dark or olive-brown without the reddish tinge so common in that 
species; the pale, oblique, metathoracic ray usually apparent but often 
obliterated. 
There are no reliable characters by which to distinguish it from the 
female of femur-rubrum ; the posterior lobe of the pronotum is usually 
less conspicuously punctured, agreeing in this respect with spretus. 
Male. —Differs from spretus in being smaller, pronotum rather more 
constricted and sub-cylindrical; eyes more round and prominent; the 
notch at the tip of the last segment less distinct, sometimes almost 
obliterated; more of the nerves of the wings dark. 
From the male of femur-rubrum it differs in usually having longer 
wings, in some individuals they are as long, proportionally, as in any 
specimen of spretus , in others little or no longes than in femur-rubrum; 
in the more slender form and smaller size; in having the apical seg¬ 
ment of the abdomen narrowed and notched at the tip; in having the 
cerci broad throughout and shaped as in spretus; in having the tooth¬ 
like appendages at the base of the super-anal plate shortened and 
broadened, and with a longer union at their base. 
It is evident from these characters that atlantis is an osculant form, 
intermediate between spretus and femur-rubrum , partaking largely of 
the characters of each, and in a few respects differing from both. 
The female approaches very near femur-rubrum, scarcely showing va¬ 
rietal differences from the female of that species; while on the other 
hand the male approaches much nearer spretus, as shown by the char¬ 
acter of the terminal segment of the abdomen, the form of the cerci 
and the length of the wings. « 
32. CALOPTENUS BIVITTATUS, Say. 
In this very common species, the vertex of the female is convex or 
but slightly depressed, and the frontal costa not sulcate; in the male 
the frontal costa is more or less distinctly sulcate. Elytra and wdngs 
but little longer than the abdomen. The last ventral segment of the 
male has the apical margin entire and circular. Pronotum with the 
sides straight, very slightly expanding posteriorly; posterior cross-in¬ 
cision distinct; posterior femora equal to or passing the abdomen. 
