BV E. MEYRICK. ' 825 



obliquely to hindmargin beneath apex ; a black somewhat inter- 

 rupted hindmarginal lin6 : cilia light brownish-ochreous, obscurely 

 barred with darker on basal half, and mixed with whitish on 

 terminal half, with a white bar at apex. Hindwings with hind- 

 rnargin rounded, strongly waved ; deep ochreous- yellow, towards 

 anal angle marked with two or three short dark fuscous lines from 

 inner margin ; a dark fuscous hindmarginal line ; cilia light 

 ochreous-yellow, mixed with fuscous towards anal angle. 



Sydney and Bulli, New South Wales ; in October, five speci- 

 mens. A distinct and very elegant species. One of my specimens 

 has (in one forewing only) a neuration which at first sight seems 

 quite abnormal, vein 7 rising from a point with 6 but quite 

 separate from 8 and 9, whilst 9, 10, and 11 appear to rise from 8, 

 and this last springs from much before the angle of the cell ; the 

 other forewing being perfectly normal. There can be no doubt 

 here that the origin of the veins is really exactly as usual, but 

 that certain portions of them have become obsolete by non-develop- 

 ment, viz., that portion of 9 which lies between the origin of 7 

 and the anastomosis with 10, and also that portion of 10 which 

 lies between its origin and its anastomosis with 11. Although in 

 the case of this species it is certainly a morbid development or 

 monstrosity, it is of particular interest, because a similar structure 

 is found normally in two other genera of the family (Acodia and the 

 European genus Mesotype), and we can see here how it originated. 

 It is particularly necessary to rightly conceive of this change, 

 because the rising of 7 and 8 of the forewings out of 9 is an 

 essential characteristic of the whole group of the Geometrhia, 

 and it is exti-emely important to show that these genera are only 

 apparently and not really exceptional. 



33. Hydr. interruptata, Gn. 



(Cidaria interruptata, Gn. X, 469, pi. ix, 6.) 



(JQ. 23-27 mm. Head, palpi, and thorax pale brownish, mixed 

 with whitish and dark fuscous ; palpi 2. Antennae fuscous, in ^ 

 serrulate, ciliations |. Abdomen whitish-fuscous. Legs dark 



