286 



Pood of the Larvcc 



The food of the larvic of Chiroiionius consists of diatoms, algae, 

 and other vegetable matter. Tanypiis is recorded as feeding upon the 

 smaller "blood worms" (Chirononms sppj^ in addition to taking the 

 same food as the latter, 



CJiaractcrs of the Piipcc 



In the Tanypimc the pupa resembles, in a general way, that of some 

 of the Citlicidcc, the thoracic segments being much swollen and carry- 

 ing a pair of simple respiratory organs on the front part, above the lo- 

 cation of the anterior spiracles of the enclosed imago. The zcing cases 

 are distinctly separated from the sides of the thoracic segments as in 

 the ChirononujKT. The thoracic respiratory organs are simple in all 

 the genera with which I am acquainted except Chirononms. In this 

 genus they consist of a stalked base terminating in very numerous 

 threadlike filaments. The pup?e of the Ceratopogonincc may be readily 

 separated from those of other chironomids by the fact that the wing 

 cases adhere closely to the sides of the thoracic segments. The abdo- 

 men in all the species of the Ceratopogonincc which I have examined 

 bears upon each segment either distinct bristles (in the terrestrial 

 forms) or protuberances (in the aquatic forms), and is of a chitinous 

 nature, retaining its form after the emergence of the imago. In the 

 other subfamilies the abdomen bears, at most, weak and numerous 

 dorsal setulse, and the whole pupal covering is of a soft nature, col- 

 lapsing after the emergence of the adult. In the terrestrial forms of 

 Ceratopogonincc the pupa is not entirely withdrawn from the larval 

 skin, those species which I have examined in this stage, and also those 

 described by others, having the last 3-4 segments still enclosed within 

 the larval exuvia. Pupse of aquatic species of Ceratopogonincc are 

 free-swimming forms which, according to observations made by mem- 

 bers of the office staff here, must make their way ashore, or to some 

 dry surface, before the emergence of the adult. The apex of the abdo- 

 men in these last-mentioned forms is furcate, the branch on each side 

 rounded in cross-section, and tapering to an acute point. This form 

 of pupa is shown in Figure 5, Plate XVII. The apex of the abdomen 

 in Chirononuncc and Tanypincc ends in two flattened processes which 

 are generally fringed with hairs. These, and other pupal structures, 

 are dealt with more fully under the different genera and species 

 throughout this paper. In the species of Tanypincc and Chirononiincc, 

 before the emergence of the adult the pupa rises to the surface of the 

 water, but, unlike the species of Ceratopogonincc, it is not necessary 

 that it reach a dry surface before the emergence of the imago, which 



