120 INSECTS. 



air contracting, and so tightening, the membrane which 

 forms the drum, or sounding-board. 



The two families which remain are the Grasshoppers 

 and the Locusts. 



There have been so many changes and interchanges 

 of the names of all these insects (including the Crickets), 

 both in various places and at various times, that the 

 reader will find it necessary to be on his guard when he 

 meets with the various generic names " Gryllus, 

 Locusta, Acrida, Acheta," &c. Thus Gryllus, formerly 

 the generic name of the Crickets, now gives place to 

 Acheta as applied to them, and is adopted, under the 

 form Gryllida3, as the family name of the Grasshoppers, 

 while similar confusing changes have been made with 

 regard to the family Locustidse. To enter upon these 

 details would be alike tedious and useless while the 

 reader is as yet unacquainted with the animals them- 

 selves ; and here, as in all cases of the same kind, the 

 first step is to study the animals and familiarize the 

 mind with their distinctive characters. With this 

 knowledge the difliculties occasioned by variety of 

 system and diversity of nomenclature, will become a help 

 rather than a hindrance in the work of obtaining a clear 

 idea of the relations and grouping of animals. 



According to Westwood, whose classification is 

 followed here, these insects are grouped (see p. 1 16) into 

 the families of Achetida, Crickets ; Gryllid<e, Grass- 

 hoppers ; and Locustida, Locusts ; the English names 

 assigned by him not necessarily according with the 

 popular use, according to which most of the Locustida3, 

 in common with the Grasshoppers, are usually called 

 Grasshoppers. 



The Gryllidae (see PL IV., fig. 4,) resemble the 



