characters we have met with, serving to separate at once all members 

 of the subfamily Hypoptinac from the other two subfamilies; this ap- 

 parently leads over to the Arbclidae, especially as the first anal vein 

 is inclined to obsolescence basad of the cross-vein. As previously re- 

 marked the subcostal cross-vein of secondaries is very variable ; in the 

 following "Key to Genera" we have used it to separate the two gen- 

 era of the Zcuzcrinae, as it is an easily recognizable feature and in 

 this subfamily seemingly constant ; there are however other points of 

 anatomical diflference, notably in the tibiae and tarsi, on which a separ- 

 ation can be made, should this prove inconstant. 



The Frenulum shows a remarkable degree of variation. What- 

 ever the phylogenetic derivation of the Cossidac may be, it is probable 

 that the frenulum is a primitive characteristic, and that those forms 

 in which it has become reduced are further removed from the com- 

 mon ancestor than the possessors of a fully developed frenulum. 



Both genera of the subfamily Zcuzcrinae, viz. Zcuzera and Ha- 

 milcara, possess a frenulum of normal length, perfectly capable of per- 

 forming its function. In the Hypoptinac a similar condition is man- 

 ifested in Hypopta and Pomcria, whilst in Ghira a gradual reduction 

 may be traced, miiuita showing a fully developed frenulum, arbeloides 

 and mucidus a short, stubby, and probably functionless one, and the 

 remaining species either mere rudiments in the shape of minute 

 bristles, or else nothing at all. In this connection we might mention 

 that all the Hypoptinac show a strongly enlarged humeral area of sec- 

 ondaries, which fully supplies the place of the missing frenulum. We 

 have refrained from creating separate genera for these three groups 

 as in all other respects they are identical. Among the Cossinae, Cossula 

 is the only genus with fully developed frenulum ; a gradual reduction 

 may be traced through Toronia, Comadia and Fania to the rudimen- 

 tary condition exhibited by Acossiis and Priono.vystiis. 



The Tibiae are, in the majority of the genera, covered with long 

 hair, Prionoxystus forming in this respect an exception; the epiphysis 

 on the fore-tibiae in Zciiccra (PI. Ill, fig. 5) is enormously developed, 

 almost equaling the tibia itself in length; in Hamilcara (PI. Ill, fig. 7) 

 it is also very prominent, while in the other genera examined by us it 

 is present as a well developed, ribbon-like, chitinous plate. The mid- 

 tibiae always possesses a single pair of apical spurs. The hind tibiae 

 are in this respect variable ; the Zcuzcrinac possess a single short pair ; 

 (PI. Ill, figs. 6 and 8) the Cossinae {Toronia we have been unable to 



