458 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



a crustacean larva appears to me to be very clear from an examination 

 of the figures which I reproduce, Figs. 385 and 386, and, indeed, this 

 has already been shown by Seebach.^ 



V. 



It remains to notice a little more definitely the geological position of 

 the fossil spiders of America. Professor Cope, in view of the character 

 of the fish fauna, relegates the Florissant deposits to the later 

 Geolog-ical ji^QPgj^p or early Miocene. ^ Lesquereux, judging from the plants, 

 osi lono j.pfp,.g j^j^jg deposit to the lower Miocene or Oligocene.^ This 

 Spiders would place the spiders and the insects of these beds within 

 the same horizon, substantially, as those of tlie amber and the 

 Oeningen and other Tertiary strata of Europe. Or, as Scudder has ex- 

 pressed it, " We may therefore provisionally conclude, from the evidence 

 afforded by the plants and vertebrates, that the Florissant beds belong in 

 or near the Oligocene." The evidence derived from insects and spiders is 

 thus in harmony with that from vegetables and higher animals. 



I have attempted, by the following tabulated statement, to express ap- 

 proximately the relations of the Florissant spider bearing deposits with 

 those of Europe in which sjjiders have also been found. 



TERTIARY. 

 Plioce.ne. 



j I'pper. 1. Fresh water formations, Oeningen, Switzerland. 



Mkiiene. I Middle. 2. Sulphur impregnated strata, Radoboj, Croatia. 



( l.ower. .". Brown-foal strata of the Siebengebirge, Rhine. 



( 4. Florissant Basin, Florissant, Colorado, U. S. 



Oligocexe. i 5. Amiier, Prussian Baltic. 



( 6. Fresh water formations,* Aix, Provence.' 



EocEN'E. 7. (Tarnet Bay, Isle of Wight (Eoatypus woorlwardii). 

 CRETACEOUS. 



JURASSIC. 8. Lithographic limestone, Solenhofen, Bavaria (,PaIi>ipes priscus).* 

 TRIASSIC. 

 PERMIAN. 



C 9. Argillaceous slate, Kattowitz, Upper Silesia (Protolycosa anthro- 



CARBONIFEROUS. J cophila). 



( 10. Coal measures of Illinois (Arthrolycosa antiqua). 



' Zeitschr. deutsch geol. (iesellsch, XXIII., page 840. 



- Bull. U. S. Geological Survey Territories, 2d series, Xo. 1, 1875. 



' Report U. S. Geological Survey Territories, Vol. 7, 1878. American .Tournal Science, 

 XVII., page 279. 



* Oustalet, Recherches sur les Insectes Fossiles des Terrains Tertiaires de la France, 

 page 3(i. t)ustalet presents the various views of geologists as to the position of this forma- 

 tion, from whit-h I have placed it as here. 



'^ A well preserved Theridioid spider from Aix may be seen in "Geology and Mineral- 

 ogy," Bridgewater Treatise, by Rev. Wm. Buckland, 1). D., Vol. II., page 79, and plate 4H. 

 Fig. 12, Theridium bucklandii Thorell. Gourret has recently described about eighteen Oli- 

 gocene species from Aix. Rec. Zool. Suisse, IV., page 431, 1887. 



<* A crustacean larva, see above, page 457. 



