Chirononius and other Diptera 



19 



segmental spiracles are present ; all are closed. A pair of 

 small processes were seen on the vertex of the pupa, like 

 those of C dorsalis. The pu23a has a pair of respiratory 

 trumpets, which are long, narrowed at each end, and 

 spinous. , The second abdominal segment bears a median 

 dorsal prominence beset with spines ; this 

 perhaps serves to steady the pupa in its 

 case. The tail-fin is expanded laterally, and 

 fringed with about 100 setae on each side. 



' The fresh-hatched larva does not differ 

 materially in structure from the full-grown. 

 The setae of the sensory filaments are not 

 so numerous, and the tracheal system, if 

 present at all, is not filled with air at this 

 time.' 



This book will be occupied by a description 

 of species belonging to the first group (p. 10), 

 which includes the common large red larvae 

 or blood- worms. The insect which we have 

 chiefly studied is called Clilvonomus dorsalis 

 iC. venustus is a synonym). There are other ^p'/''*^''^, !''"'"" 



^ >J J I pet of Chiron o- 



larvae which difier only in minute details, "1*^^^ (Orthocia- 



"^ _ dius). X 100. 



such as the number and form of the joints 

 of the antenna. For most purposes all large red larvae 

 may be taken as practically identical ; by large is meant 

 a larva nearly an inch long when full-fed. 



We have noted elsewhere (p. 150) the remarkable variety 

 of structure presented by the larvae and pupae of the 

 Chironomidae, and even by those of the single genus 

 Chironomus. 



Baron Osten 8acken divides the order Diptera into ckirono- 



^ , , -, mus and 



three sab-orders : — other 



I. Orthorrliaplia Nemocera. II. Orthorrhaplia Brachy- ^^ ^^^' 



cera. III. Cyclorrhapha Athericera. 



The names adopted for these sub-orders have the 



c 2 



Fig. II 



Re- 



