156 NATURAL HISTORY OF AQUATIC INSECTS CH. 



graver. The digestive 

 tube is straight and 

 simple, and appar- 

 ently adapted to the 

 wants of a carnivor- 

 ous animal. I have not 

 been able to identify 

 the small particles of 

 food which are occa- 

 sionally seen within it. 

 There is a pair of very 

 delicate air-tubes run- 

 ning along the body. 

 The pupa swims at the 

 surface, and can attach 

 itself to floating objects 

 by means of two spines, 

 which project from the 

 extremity of the ab- 

 domen. It does not 

 completely free itself 

 from the larval skin, 

 but carries the loose 

 and shrivelled envelope 

 about, attached to its 

 tail. Some other species, 

 of quite different mode 

 of life, do the same. 

 Most species of Cera- 

 topogon are not aquatic 

 in their early stages, 



FIG. 46.!, Larva of Ceratopogorr, 2, head fo u ^ }} ve under the bark 

 of do. ; 3, mandibles ; 4, double outline, 



showing flexion of the body in opposite ^f J^eeS. . DufoUH IS 

 directions while swimming. 



