THE HOUSE-CRICKET 193 



the top of the joint which is called the tibia. Here are 

 two oval membranes of unequal size, the larger being on 

 the outer surface and the smaller on the opposite one. If 

 the tibia of the cricket is mounted whole in Canada balsam, 

 both will be seen together when the part is examined 

 with a lens. A large nerve with a ganglion on it is found 

 within the tibia, and the structure of the parts strongly 

 suggests that they are useful in hearing. The organ of 

 hearing occurs in both sexes ; the male cricket hears the 

 sound which he produces, and the female hears the call 

 of the male. Many insects which emit sounds have 

 similar membranes, either placed in the tibia of the fore 

 leg, as in crickets, or near the base of the hind leg ; in 

 fact, when an insect utters a sound audible by man, its 

 own auditory organ can generally be pointed out. It 

 ought not, I think, to surprise us greatly that there are 

 a good many insects which have the supposed auditory 

 organ without any known means of producing sound. 

 They may utter sounds which are audible and full of 

 meaning to one another, but beyond the range of the 

 human ear. Besides it may be necessary for them to per- 

 ceive sounds which they are unable to produce. 



Nothing has been said of the two jointed tails which 

 stick out from the hinder end of the body in both sexes. 

 Possibly they are feelers which protect the hinder part 

 of the body when the head is busy guarding the mouth 

 of the hole, and other uses have been suggested. 



I should like to leave the inquirer into insect- structures 

 something to investigate without help, and I can think 

 of nothing better than the ovipositor or egg-laying forceps 

 of the female cricket. It is mechanically interesting on 

 account of its perfect adaptation to the end in view ; it 

 is not too minute nor too elaborate for the student who 

 has only low magnifying powers at command, and lastly 

 (this will be a spur to some minds) it has never, so far as 

 I know, been completely and intelligently described. I 

 hope some day to read such an account of it as may 



