STRUCTURES OF CRICKETS. 639 



so, the vertex closely merged with front of face; eyes rather small, 

 usually oval or elliptical, widely separated; ocelli variable in 

 size, form and position, sometimes wanting; antennae usually long 

 and filiform; prouotum short, broad, usually depressed above; 

 tegmina flat above, bent abruptly downward at sides, usually fully 

 developed, though (Gryllotalpinse, Myrmecophllinae and Xcnio- 

 bius) often abbreviated or even wanting; wings folded like a 

 fan, usually shorter than teginina, often very rudimentary or 

 wholly absent; fore tibiae variable in structure and usually with 

 a hearing organ on both sides; hind femora usually much en- 

 larged, though in the tree crickets (Oecanthinse) very slender; 

 hind tibiae armed above either with numerous spines or fine teeth 

 or both on each margin, except in the Gryllotalpiuae and Tridacty- 

 linae, where only the inner margin is so armed ; also armed near 

 apex with two or more pairs of subapical spurs; tarsi usually 

 three-jointed (in Tridactylinae one- or two-jointed or wanting) 

 the first joint often very long; pulvilli wanting; cerci very long, 

 hairy, tapering; ovipositor as described below. 



The name Gryllidae is derived from that of the principal genus 

 Grylhis, a Latin name for cricket. By Kirby and some of the 

 European authors the family name Achetidae is used for these in- 

 sects. The family is widely distributed over the earth, but in this 

 country the species are less numerous than those of either the 

 Acrididje or Tettigoniidae. 



The tympanum or calling organ of the males of Gryllida?, 

 when present, is, as in the Tettigoniidae, located near the base of 

 the dorsal surface of the tegniiua, but is wider and broader, ex- 

 tending across both anal and median areas of the tegniina. In the 

 males of Gryllus, as Lutz (1900) has shown, the right tegmen al- 

 most alwaj r s overlaps the left and the "file" or stridulating ridge 

 on the under side of the left is therefore rarely used, yet it ap- 

 pears as fully developed as the other. Lutz changed the position 

 of the tegniina in a freshly moulted male, placing the left one 

 above, and after they had hardened the cricket "could chirp just 

 as well as one whose tegniiua had not been tampered with, al- 

 though he was using the sound-producing organ which would nat- 

 urally not have been used at all." More than one-third of the 

 742 females of Gryllus examined by Lutz carried the left tegmen 

 uppermost, and in that sex the position of the tegmiua were dur- 

 ing life frequently changed by the insects themselves, but were 

 never so changed in the males. 



The chirps or love calls of the different species of crickets make 



