566 MICROSCOPY. 
PASSAGE or SPECIFIC CHARACTERS FROM ONE GENUS TO ANOTHER. 
—I find among the Acridide from the west a case which would 
seem to go far toward confirming the opinion of Prof. Cope, that 
often specific characters pass over from one genus to another. 
The Acrolophitus hirtipes Thos. (Gryllus hirtipes Say) forms a 
very distinct and somewhat peculiar genus; the specific charac- 
ters are also very distinct and well marked. During my connec- 
tion with the United States Geological Survey, in charge of Dr. F. 
V. Hayden I have frequently met with this species in Colorado, 
northern New Mexico, and Wyoming, but nowhere else in those 
territories or in northern Utah, Idaho, Montana, Nebraska, Kan- 
sas or Dakota have I met with any closely allied species. Recently 
the Orthoptera collected by Lieut. Wheeler during his, Explora- 
tions in Arizona have been submitted to me for examination; in 
that collection I find specimens which, in specific characters in- 
cluding even color, agree exactly with A. hirtipes, but differ in two 
prominent generic characters. 
In Acrolophitus the chief generic characters are, an erect, coni- 
eal vertex (which alone distinguishes it from all other American 
species of Oedipodini) ; a sharp elevated crest on the posterior 
lobe of the pronotum ; posterior margin of the pronotum acutely 
angled. The species collected by Lieut. Wheeler has the erect, 
conical vertex, but the pronotum is without a crest or even 4 
medium carina, and the posterior margin is obtusely rounded, 
yet the general form, size, etc., even to the hairs on the legs, 
are the same in both species; the color is exactly the same 
throughout.—C. Tuomas. 
OccurrENCE OF THE Rock Weren 1N Iowa.— Salpinctes obsoletus, 
not previously found east of the Rocky Mountain region, was ob- 
served by the writer last fall in Decatur county, Iowa. It was 
seen on several occasions, far out on the prairie, ranning over the 
ties on the railroad track, retreating when alarmed, into the 
dense prairie grass.— T. M. T., Garden Grove, Iowa. 
MICROSCOPY. 
Apertures OF Oxsectives.— It is now certain that nothing can 
be easier than to get more than 82° of rays through a balsam 
object and immersion objective, and that those accomplished mi- 
` ¢croscopists who maintained the contrary were in error in n resting 
