BY A. J. TDRXER. 557 



teyiiance, and I regard Eumelea as the genus, of all witli which 

 I am acquainted, coming nearest to the parent-stem of the 

 former subfamily, being a somewhat aberrant branch from this 

 stem. The importance of the approximation of 5 and 6 of the 

 hindwings in the Geometrince does not consist in that character 

 being peculiar to the subfamily, for it occurs occasionally, as an 

 aberrant character, in some of the other subfamilies; but in the 

 fact that, iu the former, that character has become fixed, being 

 found without exception throughout the group. 



A most important character of the higher Lepidoptera, that is 

 all except the primitive Microjjterygidce and Hepialidre, is the 

 presence of a frenulum. In certain groups the frenulum has 

 been lost, and in them its place is supplied by an expansion of 

 the base of the costa of the hindwing. In the Geometrince may 

 be found all gradations between a strong functionating frenidum 

 and its complete absence. In the lower genera it is well- 

 developed. The first stage in its obsolescence is the appearance 

 of a rounded dilatation of the base of the costa of the hindwing, 

 just be3'ond the origin of the frenulum. This is soon followed 

 Ijy the obsolescence of the frenulum itself, which usually occurs 

 most rapidly in the female sex. In the male it is longer per- 

 sistent, but becomes weak and slender; while the retinaculum 

 shilts to nearer the base of the forewing. Evidently, though 

 developed, these organs are not strongly functionating. In the 

 next stage, frenulum and retinaculum become completely obsolete 

 in both sexes. By the use of these characters, the Geometrince 

 ma}' be readily divided into three divisions, the genera which 

 may be regarded as intermediate being extremely few, at least 

 in the Australian fauna. 



Div. i. — Hindwinji with a stronjc rounded dilatation at base 

 of costa. Frenulum and retinaculum completely absent in both 

 sexes. 



Div. ii. — Hindwing with a rounded dilatation, usually strongly 

 marked, at base of costa. Frenulum in ^ usually weak, 

 retinaculum usually close to base of forewing. Frenulum in 

 female usually absent. 



