125 
species, yet there are other slight differences observable when a 
large number of specimens are compared. The eyes in femur rubrum 
* are slightly more prominent; the head, pronotum and sides of the 
thorax are usually some shade of olive-brown, varying from 
pale to almost black; the black line behind the eyes is 
quite broad, seldom broken up, and is distinct in the darkest 
specimens. The humeral (entering) angles of the posterior margin 
of the pronotum are more rounded and not so sharply defined 
as in spretus; the median carina is usually more distinct on the 
anterior lobes, while the lateral carinae are rather more obtuse and 
not so well defined; the punctures on the posterior lobe are more dis¬ 
tinct. The wings extend but slightly beyond the extremity of the ab¬ 
domen, usually less than one-tenth their length. In this species and 
atlantis the intercalate vein is present in the elytra dimly and imperfectly, 
it is true, but it can be clearly distinguished for more than half the length 
• of its course. In spretus it is wanting, its place being marked by the 
line of union between the two rows of cells. The fuscous spots or 
dots are not so conspicuous or widely spread over the apical portion 
of the elytra, and the elytra are narrower and straighter. As a very 
general rule the external face of the posterior femora is black or brown, 
the lower margin and lower half of the inner face bright coral red; 
when these colors are well defined there is a yellow space or stripe 
between the red and black; but these markings are subject to consid¬ 
erable variation, the red being sometimes entirly wanting, the external 
face dark and the lower margin yellow, sometimes the dark is re¬ 
placed, by a* pale-olive. The tibiae are most generally bright red, but 
this character is not without its exceptions. Usually there is a 
pale ray extending from the base of the wings to the posterior 
coxa, but is occasionally wanting in dark specimens, and is generally 
absent in spretus. The prosternal spine is not so distinctly quadrate 
at the base as in spretus , transverse, flattened behind and not regular¬ 
ly conical, but somewhat sub-cylindrical to the broadly rounded and 
very blunt apex. 
Fig. 23. Male . —The most constant difference between the 
species is found in the form of the last ventral 
segment of the male; in femur-rubrum this seg¬ 
ment, although strongly curved upwards, as in 
spretus , is not so distinctly narrowed toward the 
end, but rounded, and instead of being notch- 
of T femur -rub rivrh^ ° Let> toward the end, is squarely truncate, presenting 
ters have same refer- a sharp, horizontal and almost semi-circular mar¬ 
gin (see Fig. 23). Below the tip, on the posterior 
face of the segment, is a rather large, transverse, gash-like indenta¬ 
tion. The cerci are about the same length as those of the male spre¬ 
tus, and about the same width at the base. TLe little tooth-like ap¬ 
pendages at the base of the super-anal plate are elongate and slender, 
as in spretus, and are sinuate. 
In addition to the characters mentioned in the original description 
of atlantis, I would call attention to the following differences between 
it and spretus on the one side and femur-rubrum on the other. 
Female .—As compared with the female of spretus the wings are 
shorter, extending but very slightly beyond the tip of the abdomen, 
not differing perceptibly in this respect from femur-rubrum', the elytra 
are narrower, curved upward very slightly at the apex, very few spots 
