PRESENT DISTRIBUTION OF ALLIED SPECIES. 77 



are strictly confined to the Indo-Malayan region. It is, however, also related, but 

 in a secondary degree, to Enodia, Cercyonis and Maniola, which are genera apper- 

 taining to the north temperate zone of both hemispheres. 



Collates Proserpina finds its nearest living representatives in the genus 

 Delias, which also is strictly confined to the Indo-Malayan region. Thyca and 

 Prioneris are closely related, the latter of which is limited to the same district and 

 the former to the Indo-Malayan and Austro-Malayan regions. 



Thaites Ruminiana is represented in recent times by the genus Thais, which 

 is confined to the Mediterranean district, within which Aix lies. An allied 

 genus, Archon, is also restricted to the same region. Sericinus, however, and 

 Eurycus, with which we have been obliged to compare it in many points, are 

 found only in the East, the former in China, the latter in Australia; while on the 

 other hand, Parnassius, a genus it quite as much resembles, is limited to alpine 

 and subarctic regions of the northern hemisphere. 



The relations of Pamy>liilites abdita are very different. I have searched care- 

 fully for very closely allied forms among East Indian Urbicolae ; but, while it doubt- 

 less is not far removed from some of them, its more intimate relationships arc 

 certainly with insects from tropical America and especially with Pansydia and 

 Carystus. 



Three out of the five Aix butterflies, therefore, find their nearest living allies 

 in the Indo-Malayan region, one is most closely related to forms now found in 

 tropical America and one is at home in its own resting place. 



BUTTERFLIES OF THE AQUITANIAN (Lower Miocene). 



Thanatites vetula is the only butterfly yet found from this horizon, and this is 

 closely related to Thanaos, a genus belonging to the north temperate zones of 

 both hemispheres, but vastly more developed in the new world, which has at least 

 four times as many species as the old, some of them extending into the subtropical 

 regions. The genera adjacent to Thanaos are purely American, although tropical 

 or subtropical, and therefore the Aquitanian butterfly looks toward subtropical 

 North America for its relatives of the present day. 



MEMOIRS A. A. A. S. 12 



