INDItIX DlLUiOS flies. (iU'.t 



variable. Male witl) a i>air of suporior anal appeiulagt-s sprini^in^ 

 from the eud of lOtli segment aiul infi-rior anal appendages, often fused. 

 deeply fissured or notched. Male oenitai organs extremely variable. 



"\Vings held in a horizontal plani' when at rest. 



Larva: gills at the enil of tlu' dilatetl intestine, proteetcd by a small, 

 foliate opening. The anal opening eneircled by three pointed spines ; oni- 

 unpaired dorsal spine from the llthtergit and a ventral pair from the 

 11th sternit. The appendages of the male and female appearing in the 

 adult larva between the ventral spines at the border of the 10th torgit, the 

 inferior appendages of the male at the base of the dorsal spine. 



Key to Families. 



Labial palp (lateral lobe of labium) much larger than 

 the middle lobe, which is very minute ; the former form- 

 ing a mask-like segment in contact, by a long, straight 

 junction, with that of the opposite side across the 

 middle line ; the terminal segment obsolete. 



The eyes always more or less contiguous. 



The ocelli arranged in the form of a triangle around 

 the vesicle, the middle one in front, lying at its foot, 

 the hinder ones Ij'ing laterallj^. 



The antenodal nervures in superior (1st series) and in- 

 ferior (:?nd series) costal spaces in continuation with 

 each other, except the terminal one which in many 

 Libellulines is only present in the superior costal space. 



Trigone generally different in the two wings, lying in 

 the transverse axis in the forewing and in the long axis 

 in the hind-wing. 



Trigone in the hind-wing generally in prolongation of 

 the arc, in the forewing usually, widely distal to it Libellululff. 



Labial palj) (lateral lobe of labium), of nearly the same 

 dimensions as the middle lobe, of two segments, the ter- 

 minal of which is slim and pointed. 



The antenodal nervures in the superior (1st series) 

 and inferior (2nd series) costal spaces usually not in 

 continuation with each other except occasional pairs, 

 one or two of which are somewhat proximal to the 

 middle point between the node and base of wing. These 

 pairs meet at an angle which is bridged across by a 

 triangular membrane stretched tautly between costa and 

 subcosta. 



Trigone in both pairs of wings uniform or but slightly 

 differentiated. 



In both wings, the trigone an equal distance from the 

 arc. 



In the male, the anal border or base of the hind-wing 

 usually notched and possessing a prominent t(»rnus .... Acschndc . 



Key to the Sub-familie.s of thk Liv.ellulid.k. 



No projection to the hinder border of the eyes or if 

 present, then indistinctly circumscribed. 



Anal bi-)rder of the hind-wing in both sexes rounded or 

 straight. ' 



No tuft of hairs at the distal end of the anterior 

 femorie. 



12 



