BY B. J. TILLY Alii'. 



865 



many claval areas preserved at Ipswich, none but those of the 

 highly specialised Willcoxiidae are of the Ftugoroid type, it 

 would seem fairly certain that these two fossils may not be 

 classed with the Fulgoroidea. They are better regarded as be- 

 longing to a separate subfamily of the Scytinopteridae, from 

 which, perhaps, the Cixiidae arose later on, by specialisation of 

 the veins of the clavus. I propose to name this subfamily the 

 Mesoeixiinae, from the name of the best preserved of the two 

 genera. Mesocixius, n.g. ; the other genus is Triassocixius, n.g. 

 We may now sum up the above results as follows : — 



(1) In the Upper Permian, both in Russia and Australia, the 

 first true Homoptera were present in the form of a single family 

 having very primitive venational characters, viz. the Scytinop- 

 li ridae, represented by the three genera Scytinoptera Handl. 

 (Kama River, Russia), Permoscarta Till. (Newcastle, N.S.W.) 

 and Permofulgor (Belmont, N.S.W.). 



(2) In the Upper Trias of Ipswich, the Scytinopteridae were 

 still the dominant family of Homoptera, being represented by 

 no less than six genera. The Ipsviciidae were a highly spe- 

 cialised offshoot from this ancient family. Nothing like them 

 is known elsewhere, either fossil or recent. Amongst recent 

 families, the Jassidae were present at Ipswich, and represented 

 by three genera. Other existing families were not represented 

 at Ipswich, so far as known. 



(3) In the Lias of the Northern Hemisphere, true Scytinop- 

 teridae appear to have become extinct. True Fulgoroids, Jassids 

 and also Cercopids (Handlirsch's Procercopidae) were present. 



It is interesting to note that, at Ipswich in the Upper Trias, 

 the Homoptera formed nearly 20 per cent, of the total insect 

 fauna, as preserved in the fossils, while at Belmont and New- 

 castle (calculated on a much smaller number of preserved forms) 

 they formed 50 per cent. In the Lias, the Homoptera were 

 only 6.6 per cent, of the total insect fauna. This percentage 

 decreased to 4.5 in the Tertiary, and to 3.6 at the present day. 

 The drop in the percentage from the Ipswich Trias to the Lias 

 is due in part to the dying out of the Scytinopteridae, but more 

 to the great rise in the representation of other Orders. If 

 further evidence were needed of the approximate age of the 

 Ipswich Beds, the percentage of Homoptera would place them 

 definitely between the Upper Permian of Newcastle and the Lias 

 of the Northern Hemisphere, but somewhat closer to the latter 

 than to the former. 



