48 



TERTIARY INSPECTS OF NORTH AMERICA. 



Order ^R^NEIDES Latreille. 



As stated above, by far the larger part of the fossil Arachnides known 

 are true spiders, about one hundred and ninety species having been 

 described from the Tertiary deposits of Europe, and more than thirty being 

 added l<> the total list in this volume. These last are distributed among 

 the larger groups as follows: Saltigradse (all Attides), three; Citigradse, 

 none; Laterigradse (all true Thomisides), three; Territelariae, none; Tubi- 

 telarisc (Agalenides, one; Drassides, five; Dysderides, two) eight ; Retite- 

 lari.Te (all Theridides), four; Orbitelarise (all Epeirides), foil rteenzz thirty- 

 two. By this it appears that nearly half are Epeirides, and that after these 

 the Drassides are best represented. A comparison of this result with the 

 fossil spiders of Europe is shown by the following table, in which the per- 

 centages of the groups represented are compared in each country with the 

 total representation in each : 



Percentages of groups of Tertiary spiders in Europe and in America. 



This shows that America is far the richer in Orbitelarise, and Europe 

 much better represented in Retitelarise, less but still considerably better in 

 Laterigradae and Tubitelarise, while the Saltigradae have an almost equiv- 

 alent representation in the two countries. 



If, however, we eliminate from the inquiry the species entombed in 

 amber, and compare only those recovered from the rocks in which the\ 

 have been preserved, w r e shall reach perhaps a more just comparison, 

 although the data will be far more meager, America with its thirty-two 

 species being actually better represented than Europe with its twenty-two 

 sjiccies, all belonging to the same five larger groups which are represented 

 in America. 



