892 MESOZOIC INSECTS OF QUEENSLAND, vii., 



NOTE ON THE PHYLOGENY OF THE HOMOPTERA. 



A study of the known Homoptera from Permian and Triassic 

 strata should now convince us that the forms which I have 

 included under the family Scytinopteridae represent very closely 

 the original type of tegmen for this Suborder. There was little 

 or no fusion of the veins at the base of the wing, and great 

 diversity of the manner of branching of R, M and Cu. The 

 clavus was marked off from the rest of the wing along a fairly 

 straight vena dividens (Cu 2 )> and its anal angle was more or 

 less rounded, not angulated. Either three, or only two, anal 

 (or claval) veins were present, without any approach to union 

 of 1A with 2A to form a Y-vein. This type, as represented by 

 Scytinoptera in the Upper Permian, or by the allied Mesoscytina 

 or- Chiliocycla of the Upper Trias of Ipswich, is not very far 

 removed from the Palseohemipterous genus Prosbole, from the 

 Upper Permian, from which I have already pointed out that 

 the Triassic Dunstaniidae, and therefore the whole of the Heter- 

 optera, may be derived. 



As far as we know at present, the only recent family that 

 appears in the Trias is the Jassidae. The Ipsviciidae are to be 

 regarded as an early specialisation of a remarkable kind, pos- 

 sibly foreshadowing the later Cercopidae, but almost certainly 

 not ancestral to these latter. They may be considered as having 

 died out, leaving no recent representatives. True Cercopidae 

 appear first in the Lias, there being no reason, so far as I can 

 see, to doubt that Handlirsch's Procercopis belonged to this 

 family. True Fulgoroids also appear for the first time in the 

 Lias (genus Fulgoridium Handl.) . But this great group, which 

 in many respects represents the highest development of the old 

 Auchenorrhynchous stem, may well have originated amongst the 

 Cixiid-like forms of the subfamily Mesocixiinae within the family 

 Scytinopteridae, by development of the claval Y-vein from' the 

 more primitive Scytinopterid condition. 



The oldest known Psyllid is Triassopsylla from the Upper 

 Trias . This family is also known from the Lias. The Aphididae, 

 Coccidae and Aleyrodidae are later and more specialised de- 

 velopments from the same stem as the Psyllidae. 



Structurally the Cicadidae are undoubtedly archaic in many 

 of their characters. But they are not found fossil before the 

 Cretaceous, and the origin of the family is at present a mystery. 

 They are undoubtedly closely allied to the Cercopidae. Ancestors 



