7154 CHARLES PauLt 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, aad 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 lke- 
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, 
