BY R. .1. TILLYARD. 177 



Mesophlebia, is the condition that would be expected to be found 

 in Triassic dragonfiies from the Northern Hemisphere, if such 

 were available. Similarly, it will be seen that the Caddis-flies 

 described in this paper are definitely more archaic than the 

 known Liassic forms. The value of the Ipswich fossils, there- 

 fore, lies in this, that they are gradually filling up the gaps left 

 in Insect Phylogeny, by the unfortunate hiatus in the Trias of 

 the Northern Hemisphere. Whether we designate these fossils 

 as Triassic or Trias-Jura matters little, in comparison with the 

 fact that they contain, amongst their number, forms which, if 

 they were ever present in the Northern Hemisphere, could only 

 have been Triassic. 



Chiefly as a result of the interest attached to the specimens 

 described by me from Mr. Dunstan's 1909 collection, further 

 work was carried on at Ipswich in 1915-16. Owing to the sharp 

 angle of dip, the fossil bed cannot be followed down very far 

 without removing a great deal of overburden. Under Mr. 

 Dunstan's close supervision, this has been carefully carried out 

 by Mr. Wilcox, the shale being removed in large pieces to the 

 Geological Survey in Brisbane, where it was delaminated with 

 great care. The rock taken from some distance below the 

 originally exposed surface has proved hard, and not easily 

 delaminable. It would also appear to be much poorer in insect 

 fossils than the rock nearer the surface; but this may be, in 

 reality, only due to the difliculty of splitting it up sufliciently. 

 The result of the examination of a considerable quantity of this 

 rock has been the formation of the new collection of Ipswich 

 fossil insects, which I hope to deal with in this series of papers. 

 Mr. Dunstan informs me that the total number of specimens 

 approaches two hundred. Most of these, however, are either 

 Coleopterous elytra, Blattoid tegmina, or fragments of wings 

 that do not merit a name; so that the number of recognisable 

 new forms will be very much smaller. The study pf these forms 

 is a matter of great difliculty, requiring much care and maturity 

 of thought. With an entirely new type of wing, it is much 

 wiser to withhold publication for at least a year, while the 

 peculiarities of the venation can be turned over and over in one's 

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