J^OETH AMERICAIsr DIPTEEA. 



TABLE OF THE FAMILIES OF DIPTERA. 



1. Flics of a leathery or horny structure, living parasitically in the aJult 



state upon warm-blooded vertebrates; iiead small, either closely 

 united to the eniarginate anterior piirt of the thorax or folding back 

 into a groove upon the dorsum ; mouth-part incomplete, the palpi 

 wanting; legs separated by the broad sternum ; abdomen indistinctly 

 segmentated; claws well developed. Pitpipara. ... 43 

 Flies of softer structure, never living parasitically in the adult state 

 upon vertebrates; head separated from the thorax by a free neck. 2 



2. Antennie many-jointed, often longer than the thorax, the two basal 



joints, only, differentiated, the remaining joints usually distinct ; 

 palpi composed of three or four joints, usually elongate; anal cell 

 rarely closed or narrowed in the margin. Nematocera. . ?, 



Antenna; rarely as long as the thorax, composed primarily of three 

 joints, the third of which may V)e simjjle or complex (that is com- 

 l)osed of more or less distinct animli or segments,)* with or without 

 a ternnnal or dorsal arista or terminal style; anal cell closed before 

 the border, or, distinctly narrowed in the border, or, if of other 

 structure, the antennae composed of three simple joints with or with- 

 out an arista or style; palpi rarely much elongate, composed of 

 from one to three joints, or rudimentary. .... 14 



* To the beginner there will be several families here which will cause 

 doubt; they are especially the Sh/mlit/o', Bihionidit', Oriilnic/i/iilHld', and 

 some of the X/jlophagind'. The Sitjin/idir are small, thick-set flies, with 

 the antennae not longer than the head, composed of ten joints, the veins of 

 the wings weak and the neuration incomplete. In the Bihionidw the anten- 

 nae have from nine to thirteen joints closely united, altogether no longer 

 than the thorax; there is no discal cell. Orphnejihila is composed of species 

 not more than three or four millimeters in length ; the antenna; are appar- 

 ently three-jointed with a ternn'nal arista; under close examination, how- 

 ever, the third joint will be found to be composed of three segments and 

 the arista of seven. The Xz/loji/iar/ina: will be best distinguished by the 

 comi)lete neuration and the closed or narrowed anal cell. In all cases 

 where the palpi are found to be composed of four joints the sjiecies may be 

 unhesitatingly placed among the jVciiiiilorcrd. 



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