GRYLLIDjE. 251 



considerable time. In ordinary cases, they traverse 

 but short spaces at a time ; but when any change of 

 place becomes requisite, they are able, like their re- 

 latives the locusts, to fly both high and far. Indeed, 

 it is very probable that the relations given by travel- 

 lers respecting the immense congregations and flights 

 of what are vaguely termed locusts, ought sometimes 

 to be referred to certain kinds of Gryllidee. 



Although these insects do not leap so powerfully 

 | as the true locusts, the structure of the hinder legs, 

 | the instruments by which they accomplish it, is pre- 

 cisely similar. The thigh is much elongated, and 

 I thickens gradually as it approaches the body; the 

 [knee is likewise a little swollen to afford room for 

 the somewhat complex articulation which unites it 

 to the tibia. Along each side of the thighs, are three 

 longitudinal ridges ; and on the upper and under sides, 



double row of quadrangular elevations, placed 

 obliquely, and somewhat resembling the surface pro- 

 iuced by plaiting together two pretty broad thongs. 

 What may be called the knee-pan, has a cavity in 

 Jie centre, adapted for the reception of the head of 

 ;he tibia, and in this sinus the condyle of the tibia 

 ivorks. Besides the central process or condyle of the 

 ibia, there are two lateral ones which also work in 

 i sinus of the knee. The motion of the tibia is there- 

 fore semirotatory up and down, as upon a pair of 

 rivots, and all the parts being connected by means 

 if strong ligaments, dislocation cannot easily take 

 )lace. When this is considered in connection with 

 .he state of the muscles of the thigh, thickened for 



