270 



The Wing-Venation of the Leptoperlidae (Order 

 perlaria), with description of a new species 

 of the Genus dinotoperla, from Australia. 



By R. J. Tillyard, M.A., Sc.D. (Cantab.), D.Sc. (Sydney), 



C.M.Z.S., E.L.S., F.E.S., Entomologist and Chief of the 



Biological Department, Cawthron Institute, Nelson, N.Z. 



(Communicated by A. M. Lea.) 

 [Read October 13, 1921.] 



The Leptoperlidae are the dominant family in the Stone- 

 fly Fauna of the Southern Hemisphere, numerous species 

 occurring in South America, New Zealand, Tasmania, and 

 Australia. Owing to the fact that they are inert insects, 

 seldom seen flying, and also because most of the species 

 appear in the winter, or early spring, in Australia, very 

 little is known about them here; and it is curious to note 

 that only a single species, ParanotOperla australica, End., 

 from south-western Australia, has, so far, been described 

 from the mainland. They are, however, common on all fast 

 mountain streams, and especially abundant in Victoria and 

 Tasmania ; while, even in so warm a climate as that of Sydney, 

 at least two species can be taken fairly commonly from July 

 to October. 



In a recent paper ("Canadian Entomologist," 1921, pp. 

 39, 40) I have tabulated the characters of the various families 

 of the Order Perlaria, and have also given a dichotomic key 

 to the same. The Leptoperlidae may be briefly defined as 

 follows : — 



Small to medium-sized stone-flies of a somewhat gen- 

 eralized structure, the mandibles, clypeus, and labrum normal, 

 the palpi with short segments, the anterior coxae placed 

 widely apart, the tarsi with segment 2 shortest, 3 longer 

 than 1, the cerci usually long to moderately long, never 

 reduced to 5 segments or less. In the forewing, Rs is usually 

 either simple or once forked, very rarely three-branched ; 

 Cu x is simple or forked; 1A is simple; 2A is generally forked, 

 rarely simple.* 1 ) There is no anastomosis or transverse chord 

 in either wing, but the distal half of the forewing, and fre- 

 quently also of the hind, carries more or less numerous and 

 irregularly placed cross-veins. A complete series of inter- 

 cubital cross-veins is present in the forewing, together with 



(i) It is possible that these veins are 2A and 3A respectively, 

 and that both trachea and vein 1A have disappeared. 



