ARA^CHMIDES Latreille. 



Up to the present writing a little more than two hundred and Hfty 

 species of Arachnides have been described as found in Tertiary deposits. ( )t 

 these about one hundred and ninety are true spiders, while the reniaindei- 

 are mostly Acarina (thirty-seven species), Opiliones (eleven species), or Cher- 

 netidas (nine species). All but a single species, Aranea Columbia', described 

 below, are from European beds, and nine-tenths of them are preserved to us in 

 the Eocene amber. Were this means of restoring the ancient Tertiary fauna 

 unknown to us, our information at the present day would be based upon 

 twenty-four species, although in addition to these half a dozen more are 

 indicated by simple reference to genera or families. This number is already 

 exceeded by those described below from a single localit}-, Florissant alone 

 having yielded more than thirty species. Whether we examine the Ameri- 

 can or European species preserved in stratified deposits we find an almost 

 total absence of any but true spiders or Araneides; in each (including the 

 one herewith figured) a single species of Acarina has been described, though 

 a number of others are credited without description to European strata. 

 In Prussian amber, on the contrary, though Araneides are vastly in the 

 majority, the other groups of Arachnides form 27 per cent of the entire 

 number of species, distributed mainly in tlie three groups mentioned above. 



This greater proportion of true Araneides in Tertiary deposits, a pro- 

 portion exaggerated at the present day, can scarcely be well compared to 

 what we find in the older deposits, from the extreme paucity of their 

 remains in the latter. Brodie has found only a single species (which he 

 considers a true araneid) in the secondary strata of England, and the 

 European Jura has furnished merely half a dozen arachnids (nominal species, 

 perhaps reducible to four), of which only a single one is referable to tlie 

 Araneides, Hasseltides, considered one of the Agalenides by Weyenbergh. 

 In the paleozoic formations, again, a dozen species are known, all I)ut tln-ee 

 of which have been considered scorpions, Phrynidae or Chernetidae, or else 

 placed in their vicinity, while one of the other three has not been placed 



45 



