LUTZ, LIST OF GREATER AXTJLLEAX SPIDERS 



137 



only known living representatives are in ]\Iaclagascar. Furthermore, the 

 only other genus of the family is confined to Patagonia. Had it not 

 been for the fortunate find in Baltic amber Ave would not know that the 

 family ever occurred in the northern hemisphere and a land bridge from 

 Patagonia to Madagascar in the most direct way compatible with sea- 

 bottom contours would receive additional strong support. As it is, it 

 seems more probable that this was once a fairly widespread family and 

 it certainly occurred in northern Europe. We know that prior to the 

 glaciers the climate of the Xorth Polar regions was mild or even tropical 



Fig. 6. — Distrihiitioii of certain genera Tcnoxon from Baltic amher 



1. Segestria; 2, Dysdera; 3, Eresus ; 4, AmauroMus ; 5, Archwa; 6, Agelcna; 7, 

 Anyphcena. Only certain points in some of the ranges are indicated. The lines 

 represent possible routes of dispersal. 



iuid hundreds of circumpolar species point to the interchange of fauna 

 between Eurasia and Xorth America, where land bridges, if they ever 

 existed, would not need to be long, so that it really seems quite probable 

 that the genera of Archaeidse which are found in Madagascar and Pata- 

 gonia respectively are merely remnants either of a formerly widespread 

 family or of a northern family which was driven south by competition 

 with new forms. Such a movement is supported by mammalian fossils 

 and seems more likely than a South Polar connection. 



Eeference has been made to Pocock's list of seventeen recent genera 

 found in Baltic amber. Of these we cannot consider here Aranea and 



