THE CKANE-FLIES OF NEW YORK PART II 753 



head on the pronotum are the two breathing horns, which are variously 

 developed in the different tribes and genera and furnish invaluable bases 

 for classification. The leg sheaths usually far exceed the short or but 

 moderately elongate wing sheaths. The abdominal segments are often 

 provided with a subterminal armature of stiff setae, or spines. At the 

 posterior end of the body, the 'last two segments (cauda) are variously 

 modified to inclose the sexual organs of the adult flies. 



The head 



The head is usually small and flattened, occupying the anterior ventral 

 part of the body. The eyes differ in size in the various groups, in some 

 (Erioptera, Elephantomyia) being larger in the male than in the 

 female ; in the male sex they are approximated on the median line above 

 or beneath. 



The front between the eyes is usually narrowed behind, delimited by 

 the inner margin of the compound eye, narrowed at the posterior end, 

 and bluntly rounded or pointed at the apex. This part is described 

 herein as the Idbrum, or labral sheath. It contains the fronto-clypeus 

 and the labrum of the imago. At its tip it bears two more or less diver- 

 gent lobes, these being in some cases closely approximated so as to appear 

 as a single lobe; these are herein termed the labial lobes or sheaths, and they 

 contain the so-called paraglossae of the adult fly. 



On either side of the labral sheath, and usually divergent and lying 

 along the posterior margin of its face, are the sheaths of the maxillary 

 palpi, which in most cases extend beyond the knee joint of the fore legs. 

 In almost all the Limnobiinae these are short and stout and almost 

 straight, but in the majority of the tipuline forms they are curved at 

 their tips, which in most species are actually recurved and offer an easy 

 means of distinguishing members of this subfamily. In many of the 

 Limnobiini the margins of the cheeks project as flattened ledges overlying 

 the joint of the fore legs. 



The antennae arise from above or between the eyes and bend laterad 

 and thence caudad around the eyes, in some forms, such as Elephant- 

 omyia and the males of other species, lying across the face of the eyes. 

 The antennae usually end just beyond the roots of the wings, but in the 

 males of some species (Eriocera) they extend beyond the tips of the wings. 

 The basal segments (scape) of the antennal sheath are often armed with 



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