416 



ancestry of the forms at present known thence. From the large 

 amount of generic diversification in the group, we may infer with 

 some probability a correspondingly long period of isolation. We 

 shall see hereafter that the Concliylidce afford a quite similar 

 instance of a peculiar group, from the characteristics of which 

 precisely the same inferences may be drawn. In connection with 

 the development of this group derivable from Capua, the pre- 

 dominance of Capua itself and its close ally Dichelia in the 

 Australian region is of considerable interest. The first of 

 these genera is represented by twelve, and the second by 

 thirteen species, both genera extending to New Zealand ; whilst 

 in Europe and America they are very sparsely represented ; in 

 fact, of Capua only three other species are known. Besides these 

 there are four other nearly allied endemic genera, including 

 seven species ; so that in fact three-fourths of the peculiar 

 Australian genera of the family are traceable to this source ; and 

 as out of the twenty-one genera described seventeen are endemic, 

 this disproportion is very marked. 



Of the rest, the cosmopolitan genera Tortrix and Caccecia are 

 represented by numerous forms of no marked peculiarity ; these 

 genera are doubtless of great antiquity. Cacwcia is especially 

 predominant in New Zealand, where all the species appear to 

 belong to a special group with more elongate palpi, suggesting 

 a limited origin. There are also three other endemic genera of 

 this group, all moderately nearly allied to Tortrix, and two of 

 them extending to New Zealand. Finally there is the very 

 singular genus Mictoneura, wholly remote from all others ; so far 

 as can be judged at present, it seems probable that we have here 

 a last surviving relic of an extinct group, possibly indicating the 

 transition from the Tortricina to the Pyralidina. 



All the characteristics of the fauna will therefore agree in 

 indicating great isolation, and from the limitation of forms may 

 be inferred the remoteness of the period at which the isolation 

 began. New Zealand is distinguished by a much greater limi- 



