DESCRIPTIONS OF AUSTKALIAN ^SCHNINiE. 19 



There are two points o£ great interest in connection with the group 

 Petaliini, to which this insect belongs. They are (1) the question of its 

 ^schnine affinities, (2) its remarkable geographical distribution. I propose 

 to deal briefly" with them here : — 



1. The -ffischnine Affinities of the Petaliini. 



I have already dealt with this question in a former paper (loc. cit.). Some 

 further strengthening of the evidence in favour of the position maintained in 

 this paper is afforded by the following points : — 



(a) On making a further study of the labium of the larval exuviae, I find 

 that I had figured as the suture of the movable hook a crack or bent which 

 •occurred below it on one side. By warming the labium in water and 

 spreading it out under a glass slide, I have been enabled to draw it correctly, 

 and offer the amended figure herewith on Plate 5. fig. 12. It will be seen 

 that the structure is almost exactly of the same form as that of Aastroceschna 

 mnicornis pulclira, fig. 3. 



(b) The form of the ova is, as expected^ distinctly ^schnine, corresponding 

 to the generalized ^schnine ovipositor possessed by the female. 



(c) The habits and flight of the species, so far as I have been able to study 

 them, are distinctly ^Eschnine. 



The upward curving of il/g at the beginning of the pterostigma has been 

 ab-eady noted as important evidence in favour of the ^schnine affinities of 

 the group ; and also, of course, by the same reasoning, we must regard the 

 'Cordulegaster type of wing as an independent convergence towards the 

 Petaliini. The rounded lobes of the anterior hamuli in the male of Austro- 

 petalia suggest some resemblance to the corresponding structures in Cordule- 

 gaster, but the point does not seem to me of great importance. In the larva, 

 the structure of the head, labium^ and antennse are distinctly jEschnine. The 

 form of the abdomen^ however, is unparalleled in any group, and suggests 

 «oine specialized larval habit not adopted by any other group. Possibly it is 

 •connected with the fact that the larvse dwell in small creeks just above 

 exceedingly precipitous cascades and waterfalls, and are able to use their 

 lobate abdomen in some manner to prevent themselves from being swept away. 



2. The Geographical Distribution of the Petaliini. 



From Chili six species have been recorded, referable to three genera. 

 JFrom Australia only one species is known. The group does not occur else- 

 where, and has no near allies. The four genera comprised within it are, 

 however, very closely allied, and might even strictly be considered as only of 

 subgeneric rank. 



This peculiar distribution may be accounted for in two ways : — 

 A. The existing forms may be an archaic remnant of a once exceedingly 

 .abundant group, which has since died out in all other localities. If this be 



