ARACHNIDES ARANEIDES. 51 



ft inner and either of the others; and although the proportionate numbers of 



Tnbitelari;e and Orbiteluriie of Florissant and especially of the former 

 group are UK in- nearly like those of Rott, the representation of the groups 

 in general allies Florissant on the whole with the Oligocene rather than 

 with the Lower .Miocene of Europe. 



( )f extinct genera there have certainly been proposed a very large num- 

 lier fr tiie European Arane'ulc, more than half the genera to which the 

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

 Tertiary time-; these genera include about t \vo-lifths of the species. Among 

 the genera are some remarkable forms, such as Arclucaand Mizalia, each of 

 which is considered liv Thorell and others as representing a distinct family. 1 

 T\\o tinlv 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 

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

 rded from American strata, are Titanu-ca, Tetra-'iiatha, and Nephila. 

 To .-liter into details, seventy-one genera of Araneid:e 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- 

 :i are accounted -\tinct, thirty-live from Europe, and two from America, 

 none of the>,- beinn' found in both countries. The European genera are, as 

 mav be supposed, largelv composed of amber species, no less than fifty- 

 two, including tliirtv two extinct genera, being confined to amber deposits, 

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



If it lie asked what indications the fossil spiders of Florissant give as to 

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

 can be ^j veii: that the present distribution of their allies certainly points to 

 a coiisidi-rablv war. uer climate than now, a climate which may perhaps best 

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

 >perie.s of the genera to which they belong are in general credited to regions 

 likefieorgia in this country and the two shores of the Mediterranean in 

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

 very definitely upon their immediate relationship with exotic or indigenous 

 t'. .rms. The pr -ence of species of Theridiiim, Linyphia, Tetlineus, and 

 I'.peira, includin-- two-fifths of the species, has no special significance, but 

 Thomisus, Segestria, Clubiona, Anypluvna, and Titanoeca, and especially 



"A good critiral ivvi.-w of the described fossil species of Araneides will be found iu Thorell's Euro- 

 pean Spiders, pp. 2:>3-233. 



