PALEONTOLOGY 73 



the bodies, mouth-parts, legs, and other parts of most fossils is 

 of a more fragmentary character. It is only when we come to 

 the amber fossils of Miocene age that complete whole insects 

 prevail, but owing to their comparatively recent date they lack 

 the importance and exceptional interest associated with the 

 earlier and more imperfect remains. Altogether about 11,500 

 species of fossil insects are known, and of these approximately 

 one-fifth belong to orders or families no longer existing to-day. 

 Recent advances in insect palaeontology have, to a marked degree, 

 filled in conspicuous gaps in our knowledge of the evolution of 

 most of the main orders, but we are still faced with want of direct 

 evidence from fossils with regard to the two most important 

 problems of insect phylogeny, viz., the origin of insects as a class, 

 and the origin of wings. The oldest winged insects are of Upper 

 Carboniferous age (North America), but the fact that these forms 

 are both abundant and in some cases already specialised, leads to 

 the conclusion that the earliest Pterygota must have developed 

 not later than Devonian or Lower Carboniferous times. Among 

 arthropod remains found in flakes of Rhynie Chert from the Old 

 Red Sandstone of Scotland are fragments of what appear to be 

 Apterygota, and, if this conclusion be correct, these remnants 

 constitute the oldest known fossil insects. The oldest living insects 

 are the Blattidae, which have persisted through the ages, with 

 comparatively slight evolutionary changes, from Carboniferous 

 times to the present day. 



The strata where the richest and most important recent dis- 

 coveries in fossil insects have been made are of Permian and 

 Triassic age. The fossils disclosed in these rocks have revealed 

 so remarkable an insect fauna that our whole outlook has under- 

 gone marked changes. In a few words, it may be said that these 

 discoveries have resulted in the Permian and Triassic records of 

 insect life being transformed from among the least known to 

 almost the best known geological epochs with respect to these 

 animals. The strata in question are (1) the Upper Triassic Beds 

 of Ipswich, Queensland : these were discovered many years ago, 

 but have been more carefully explored recently by B. Dunstan, 

 Queensland Goventment Geologist ; (2) the U}:)))er Permian Beds 



