190 MOSQUITOES OP NORTH AMERICA 



terminal flaps. The culicine larvae show more or less pigmentation, even upon 

 the softer parts, and certain forms like Megarhmus, and Orfhopodomyia, are 

 deeply pigmented throughout. Chitinous plates occur dorsally on some of the 

 abdominal segments in certain forms. 



Many peculiar adaptations among the larvae occur, which will be especially 

 described, so far as known, under the several species. Most of the species in- 

 habit temporary or permanent water on the groimd, a few occur in water in 

 hollows in trees or rocks, others in water held by bromeliaceous or other plants, 

 while three of our genera are of predaceous habit, feeding upon other mosquito 

 larvae. 



The pupae of the Culicini are heavily pigmented; they are furnished with a 

 pair of well-developed anal paddles ; the seventh and eighth abdominal segments 

 have hairs or very small tufts at the posterior angles, never the large tufts 

 characteristic of the Sabethini. They are free-swimming, except in Mansonia, 

 where they are attached to certain aquatic plants from which they derive their 

 supply of air. 



The tribe Culicini presents a considerable diversity of structures, although 

 good characters for generic separation are hard to find. The diversity appears 

 more pronounced in many cases in the larvae and in the life habits. The ano- 

 phelines appear to be clearly the most generalized mosquitoes, the females still 

 retaining the long palpi, which must be decidedly in the way in performing the 

 act of feeding. We think that the development from a corethriae-like ancestor 

 consisted essentially in the lengthening of all the mouth-parts for piercing, in 

 which the palpi shared. These, being in the way, have been reduced in the more 

 specialized forms, first in the females, to which they were the greatest hindrance, 

 later in the males also. The larvae also of the anophelines greatly resemble those 

 of the more generalized corethrines and of Dixa, and are the only mosquitoes 

 in which the primitive surface-feeding habit has been retained. 



The Culicini are a less compact group than the Sabethini, more numerous in 

 genera and species ajid embracing a wider range of evolutional diversity. We 

 consider the Sabethini on the whole the more specialized group, but many of 

 their characters are more generalized than those of the Culicini or even of the 

 Corethrinae. We have reference more especially to certain larval characters. 



The larvae of the Sabethini feed largely with the maxillae, the mouth-brushes 

 being poorly developed, so that when predaceous forms arise the maxillae become 

 functional as organs of prehension. In the Culicini, on the contrary, the mouth- 

 parts are more subordinated, the mouth-brushes being fully developed, so that 

 in the predaceous forms it is the mouth-brushes that are specialized into organs 

 of prehension. Again, in the Sabethini there is no ventral brush on the anal 

 segment of the larva, all the hairs being paired, while in the Culicini there is an 

 unpaired median ventral brush or rudder; we therefore consider them a separate 

 tribe. The Sabethini are not directly derivable from the Corethrinae. In the 

 larvae of the Corethrinae the ventral brush is present, while most of the species 

 have so far lost the use of the mouth-parts that the antennae have been trans- 

 formed into organs of prehension. Eucorethra only is generalized in this 



