114 
Psyche 
[June- Sept. 
Euscelidae, Euscelis. Agalliidae, Agallia. Macropsidae, 
Macropsis, Oncopsis, Neopsis. Idioceridae, Idiocerus. 
Jassidae, Jassus. Thymbridae, Nionia. Ledridae, Dory- 
cephalus, Xerophloea. Stenocotidae, Koebelia. 
Whilst certain of the proposed changes, such as the separa- 
tion of Euscelis, Idiocerus and Jassus, have been suggested 
previously by other workers, others, in particular the associ- 
ation of Bythoscopus, Hecalus, Penthimia and Gypona, are 
original, and may at first sight appear absurd. If in time the 
alterations proposed should become accepted in whole or 
even in part, it will not be the first occasion on which a 
Figure 1. Head of a nymph of Tartessus sp. ac., ante-clypeus ; 
pc., post-clypeus; f., frons; els., clypeal suture; fs., frontal suture; 
v., vertex; cs., coronal suture; eps., epicranial suture. 
knowledge of the Australian representatives of a group of 
organisms has led to a radical change being effected in the 
basic classification of the same group in other faunal zones. 
The usual arrangement of the various genera into sub- 
families on the basis of the position of the ocelli is clearly 
artificial and several workers have stressed this fact in the 
past. Nevertheless, whilst the position of the ocelli may be 
of little significance, the shape and structure of the head as 
a whole affords the most reliable single diagnostic charac- 
ter. Because certain terms will be used in referring to the 
head that are not commonly employed, a figure of the head 
of a nymph of Tartessus sp. is given with certain of the 
sutures and sclerites indicated (Fig. 1). This particular 
insect has been chosen for illustration as the front is present 
as a separate sclerite. With the backward migration of the 
dilator muscles of the sucking pump, the epistomal suture, 
which separates the clypeus from the frons, disappears; 
