754 CHARLES PAUL ALEXANDER 



spines or tubercles, and very often the organ is angulated at the end of 

 each segment of the adult antenna inside. 



At its vertex, between or just dorsad of the antennal bases, the head 

 may bear a crest which is usually bilobed and setiferous. In some species 

 this cephalic crest is quadrituberculate, there being a smaller secondary 

 crest behind or before the primary one. -In the Tipulini the crest is very 

 inconspicuous and but weakly setiferous. In most of the Limnobiini 

 it is lacking or nearly so. 



The head may be variously armed with spines, tubercles, or setae; in 

 Eriocera spinosa, for example, there are spines or strong tubercles on the 

 antennal scape, on the clypeal region, and even on the face of the eye. 

 In some cases there are setae on the front between the eyes, on the 

 clypeus, and on the cheek. 



The thorax 



The pronotum of the thorax is small. The ventral part is closely 

 applied to the head and often has small setiferous tubercles close to the 

 breathing horns. The pronotal breathing horns are variously developed 

 in the different tribes and genera, and are discussed here in general terms 

 only. 



Many species are propneustic, the pronotal horns alone being functional. 

 Other species (in Hexatomini and Eriopterini) are peripneustic, the second 

 to the seventh abdominal segments being provided with functional lateral 

 spiracles in addition to the breathing horns; other pupae have lateral 

 abdominal spiracles, but in most cases they are merely vestigial. Some 

 pupae are amphipneustic, there being in addition to the breathing horns 

 a conspicuous pair of spiracles on the dorsum of the eighth abdominal 

 segment (Rhamphidia, Ula, Epiphragma; in the typical species of Lim- 

 nobia these are present but they are small and are probably nonfunctional) . 



In the Ptychopteridae the breathing horns are very unequally developed, 

 one being enormously elongated and filiform while the other is abortive. 

 In some Tipulini (Longurio, Prionocera, Tipulodina) the horns are like- 

 wise greatly elongated, but in these cases they are shorter than the 

 body and are approximately subequal in size, or at least are not so 

 disproportionately unequal. 



In the Limnobiini the breathing horns are usually stout and broad, 

 in the typical Limnobaria (Limnobia, Dicranomyia) being subquadrate, 



