BY R. J. TILIA'AliD. 223 



The gfiuis St^eiwperla is alreatiy well known to me through a prolonged 

 study of it during my visit to New Zealand in 1919-20. While staying with 

 Professor Chilton at the Cass Biological Station in January, 1920, 1 took the 

 opportunity to collect the larvae of the only known species, S. praahia, and to 

 dissect otf their wiug-slieaths. The very beautiful wing-tracheation of this 

 insect is shown in Text-fig. 1. Apart from a certain amount of fusion of the 

 main veins at their Ijases, which is characteristic of the order as a whole, it will 

 be seen that the courses of the tracheae are exactly those of the subsequently 

 formed veins. This character indicates that no striking tracheational or venational 

 specialisations occur in this family. The imago of S. iiraMna is shown in Plate 

 XV., fig. 9. 



Lar\ae of an unknown species of titeniiperla have long been known to me 

 as occurring (juite commonly in the fa-st mountain streams of the Blue Moun- 

 tains and South Coast districts of New South Wales. In 1912, Dr. A. .1. Turner, 

 of Brisbane, captured a fine new Steiwperla at Montville, Blackall Ranges, 

 Queensland, and sent it to me. In 1915 1 visited Maleny, not far from Mont- 

 ville, and found a large Stenoperla larva fairly common there; from it 1 suc- 

 ceeded in breeding out Dr. Turner's species. Later, I both bred and captured 

 the same species at Stanwell Park, N.S.W., and have received it from Victoria 

 also. This species is described in tiie present paper, under the name S. australis, 

 n.sp. (Plate xv., fig. 10). 



The close relationship existing between the genera Stenoperla and Diam- 

 phipnoa is so evident that I propose, in this paper, to associate them together in 

 a new subfamily, Stenoperlhwe. 



The genus Eusthenia holds an intermediate position, morphologically, be- 

 tween the excessively broad, clumsily-built Tliaumatoperlinac and the slender and 

 graceful Ste)iuperlinae. A number of new sjiecies are described in this paper. 

 One of these, from Victoria, differs considerably from the rest in the shape of 

 its wings and in an importatit venational character. I have, therefore, proposed 

 a new genus Eustheniopsis for its reception. This same new genus will also 

 include tlie species lal)elled "EuMhema reticiilulti Klap." in tlie British Museum 

 Collection. 



The zoo-geographical distribution of the family is of considerable interest. 

 Eiisthenia is confined to Tasmania; Eu--^thetiiopsis, n.g., occurs in both Tasmania 

 and Victoria; Thaumaioperla is only known from Victoria; Stenoperla occurs 

 throughout New Zealand and the mountains of Eastern Australia, but is absent 

 from Tasmania; and, finally, Diamphipnoa is found only in Southern Chili. Thus 

 the family may be said to have had either a Notogaean or even perhaps an 

 Antarctic origin. As the Ewttheniidae represent the arehetypic family of the 

 Order Perlaria, the same would appear to be true of the Order. Tf this bo 

 granted, the present distribution of the Perlaria is easily understood. For, as 

 the Stone-flies spread northwards through Central America to Holarctica, the 

 three oldest families, Eustheniidae, Aimtroperlidae and Leptoperlidae, were left 

 behind, so that nothing but comparatively specialised forms is to be found in 

 the Northern Hemis]ihere. 



Tlie distribution of the family certainly presents a strong argument in 

 favour of the Antarctic Theory. For tlie Stermperlinae are represented in Aus- 

 tralia. New Zealanil and Chili, and nowhere else in the world. Such a distriliu- 

 tion is scarcely to be explained on any other hypothesis. 



All three subfamilies are represented in the ranges of Southern Victoria, 

 which may therefore be regarded as the headquartei"s of the family. 



