AEACHNIDES— ARANEIDES. 51 



former and either of the others ; and although the proportionate numbers of 

 Tubitelariae and Orbitehxrije of Florissant and especially of the former 

 group are more nearly like those of Rott, the representation of the groups 

 in general allies Florissant on the whole with the Oli^ocene rather than 

 with the Lower Miocene of Europe. 



Of extinct genera there have certainly been proposed a very large num- 

 ber for the European Araneidiie, more than half the genera to which the 

 species have been referred having been described as new and peculiar to 

 Tertiary times; these genera include about two-fifths of the species. Among 

 the genera are some remarkable forms, such as Archsea and Mizalla, each ot 

 which is considered by Thorell and others as representing a distinct family.' 

 Two only of the thirteen genera to which the American species are referred 

 are described as new, and to them are referred seven of the thirty-two 

 species. Other genera, not before recognized in a fossil state, but here 

 recorded from American strata, are Titanoeca, Tetragnatha, and Nephila. 

 To enter into details, seventy-one genera of Araneidte have been described 

 from the Tertiaries, sixty-six from Europe, and thirteen (below) from 

 America, eight being common to both. Of these seventy-one genera thirty- 

 seven are accounted sxtinct, thirty-five from Europe, and two from America, 

 none of these being found in both countries. The European genera are, as 

 may be supposed, largely composed of amber species, no less than fifty- 

 two, including thirty-two extinct genera, being confined to amber deposits, 

 besides others which they possess in common with the stratified beds. 



If it be asked what indications the fossil spiders of Floris.sant give as to 

 the climate of that district in Tertiary times, there is but one answer which 

 can be given: that the present distribution of their allies certainly points to 

 a considerably warmer climate than now, a climate which may perhaps best 

 be compared to the middle zone of our Southern States. The known living 

 species of the genera to which they belong are in general credited to regions 

 like Georgia in this country and the two shores of the Mediterranean in 

 Europe ; but our own species are so little known that nothing can be said 

 very definitely upon their immediate relationship with exotic or indigenous 

 forms. The presence of species of Theridium, Linyphia, Tethneus, and 

 Epeira, including two-fifths of the species, has no special significance, but 

 Thomisus, Segestria, Clubiona, Anyphsena, and Titanoeca, and especially 



' A good critical review of the described fossil species of Araneides will be found in Thorell's Euro- 

 pean Spiders, pp. 223-233. 



