Mr. C. H. Goodman’s Notes on the House-cricket. 201 
the right rested on the left, in the remaining five females the 
reverse. 
Various explanations have been given of the method of stridu- 
lation, but only two are possible: one by the passage of the teeth 
of the upper elytron, over some one or more irregularities, on the 
surface of the lower, or by the passage of the teeth of both elytra 
simultaneously over the nervures of the closed wings, which near 
the root present a number of hard ridges, like the edges of a 
closed fan. It is to the first of these methods that probability 
inclines, for although only one elytron could act at a time, it is 
to be noted that in some allied species only one file exists, and 
therefore only one elytron could be used to produce the sound ; 
and as in the insect under notice the right elytron almost always 
overlies the left, it is not improbable that the right or uppermost 
file only is used in producing the familiar chirping. In some 
species there exists in the elytron a very marked ridge exactly 
in the path of the overworking teeth, and an examination of the 
house-cricket shows that a portion of the inner margin of the 
elytron is turned up just at the required spot. During stridula- 
tion the legs are motionless; the elytra are slightly raised, and 
vibrate horizontally so rapidly that the eye cannot follow them. 
24,000 vibrations per second are said to be required to produce 
a sound of the acuteness with which we are familiar. 
We now come to the metathorax, with its wings and hind legs. 
The wings when folded project beyond the body of the insect, 
and it is owing to the method of folding that the whole of this 
tribe are called Orthoptera, or the straight-winged. By drawing 
out the wing the veins can easily be traced radiating in straight 
lines from the base, a strong nervure alternating with a slighter 
one, thus facilitating its closing up like a fan. There are also a 
number of cross nervures at right angles. When flying the 
creature has an undulatory motion, making long rising curves in 
the air, and then dropping again. The hind legs are composed 
of the usual joints, but are much enlarged to increase the power of 
leaping. The under side of the femur is channelled, and receives 
the tibia when the leg is quite closed. Both sides of the latier 
joint, on the hind legs, carry a set of spines directed somewhat 
downward and outward ; while at the apex are a set of large spurs, 
about nine in number, and which would effectually prevent the 
feet slipping when a leap was made. The spurs on the anterior 
and intermediate legs are much reduced in number and length. 
The last joints are the tarsi, which have at their extremity a pair 
of strong claws. Immediately below the claws is a raised brown 
reticulated disc, which I take to be a pulvillus to assist in 
climbing, as I can find no other structure answering the pur- 
pose, and there is no doubt they can easily climb a wall either 
of smooth wood or still smoother varnished paper. They do 
