BY E. MEYRICK. 1137 



related. The Larentiadae are without doubt derived directly from 

 the Monocteniadae, originating from a type closely resembling 

 Dlchromodes, by strong anastomosis of vein 8 in the hindwings 

 with the cell-margin. The Desmohathridae may also be certainly 

 regarded as springing from a form nearly allied to Xenomusa. 

 The Geometridae and Boarmiadae appear to me at present to be 

 derived from a common ancestor approaching Aspilates, but the 

 actual line of connection is not yet quite clearly made out. 



Within the limits of the family there is considerable variation 

 in superficial characteristics, some of the earlier genera being very 

 Bombyciform in appearance. An interesting structural character 

 which is very common in this family and very unusual in any 

 other is found in the uniserial pectinations of the antenn?e ; nearly 

 three-fourths of the species of Monocteniadae, including the most 

 dissimilar groups, show this character, which appears elsewhere in 

 the Lejndojjtei^a only in isolated instances. The larvse are at 

 present little known ; but some, at least, have twelve perfect legs 

 instead of ten, and moreover possess rudiments of the other two 

 pairs ; this is what one might expect in an ancestral group, and 

 it would not surprise me if larvae of this family were hereafter 

 found with the full complement of sixteen perfect legs. 



The geographical distribution of the family shows very markedly 

 the usual features of an ancient group, struggling with difficulty 

 to maintain itself against numerous newer and improved forms. 

 There are a certain number of small, scattered, and fragmentary 

 genera, occurring almost at random throughout the old world, and 

 nowhere dominant ; and there is also a specially developed later 

 group (that of Taxeotis and Dichroviodes) practically confined to 

 Australia, originating there under the protection of a situation 

 which probably long excluded dangerous competitors, and hence 

 much better represented in number of species. I conceive that 

 the immediate ancestors of the Dichromodes group, residing 

 probably in Southern Asia, gave rise to two separate branches of 

 descent, one being the Dichromodes group, which arose within 

 Australia from emigrants who made their way thither ; and the 



