SUB-ORDER—THYSANURA. 17 



to the average person. This group includes "spring- 

 tails," which are minute creatures, white or cream in 

 colour, and seen hopping about after rain or in 

 damp weather. Those that leap do so by means 

 of two elongate processes at the under-side of the 

 anal end of the body. These are said to act like 

 a spring. They seem to leap at random. They 

 are elongate insects very like small grubs with 

 curved abdomen and large head. There are not 

 more than 6 abdominal segments. On the under 

 side of the body near the first segment is a "ventral 

 tube," the use of which is unknown, but which is 

 an important feature of the group. 



Lipitra is the common Australian type. (Plate 3, 

 Fig- 3-) 



