238 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
First Method. — If the wing-cover of a male of our common large 
Field-cricket (Grylliis) be examined from above there will be 
noticed near the base a strong, depressed transverse vein. On 
the under surface of the wing-cover the vein projects as a con- 
spicuous raised bar and bears a continuous row of very fine, 
transverse, file-like, sharp-pointed teeth projecting downward 
and inward (toward median line). At the end of the vein, 
between it and the inner margin of the wing-cover, is a tuft of 
short hairs; in front of these (nearer the base) is a crescentic 
transparent spot whose outer edge is faintly concave, forms a 
Fig. 
20 21 
20. — Portion of tegmen of Broad-winged Tree-cricket {Oecanthus latipennis), showing 
file (A) and scraper (B) used in sound production. (After Fulton.) 
Fig. 21. — Stridulating teeth on tegmen of House Cricket {Gryllus domesticus) . 
Landois.) 
(After 
part of the inner edge of the wing-cover, and is slightly browned 
by a heavier deposit of chitin or pigment. This edge forms a 
sharp scraper which rasps on the teeth of the underside of the 
other wing-cover, setting both tegmina into vibration and pro- 
ducing the characteristic chirp. Usually the right tegmen over- 
laps the left, but each bears a file and scraper and they can 
perhaps be used interchangeably in stridulation, — or possibly 
there are right- and left-handed Crickets! In the Bush-katydids 
(Scudderia) the left tegmen overlaps the right, its scraper is 
apparently lacking, and the file on its under surface is much 
better developed than on the right tegmen. The file with its 
row of teeth may be readily seen under the compound microscope 
in surface view, and the teeth show especially well when mounted 
in profile. When about to stridulate, the Cricket elevates the 
