ANCESTRAL SPIDERS AND THEIR HABITS. 



451 



Climate. 



from its general aspect, as displayed in the figure alone, I would suspect 

 it to be a young female Nephila plumipes. I have specimens of a species 

 collected by Mr. C. H. Townsend, at Swan Island, Caribbean Sea, which in 

 size and general appearance more closely resembles Scudder's description of 

 Pennatipes than the modern Plumipes. The femoral brush is lacking 

 in these specimens, as it is in Scudder's fossil (although there they may 

 have simply been worn away), and the shape of the abdomen is also cylin- 

 drical, as with Nephila pennatipes, instead of being quadrate as with our 

 species. We have thus a living Orbweaver which, as far as it is possible 

 to judge, differs little from this ancient aranead. 



On the presence of this fossil species alone I would assimilate tlie climate 

 of the ancient Florissant Lake to 



that of a region even 



further south than tliat 

 assigned by Mr. Scudder. 



Scudder ^ describes a fossil 

 Tetragnatha, T. tertiaria, which 

 he thinks does not appear to 

 have any special affinity with 

 the American species with which 

 he has been able to compare it, 

 being stouter bodied than they. 

 His conjecture, however, is hard- 

 ly a true one, that the presence 

 of this genus in the neighbor- 

 hood of the lake deposits of 

 Florissant indicates a warmer cli- 

 mate than the present. Tetrag- 

 natha, in several species, has a 

 range over the wliole of the 

 United States, and I have fine 

 specimens from as far north as the borders of Alaska. They are extremely 

 numerous in such a climate as Philadelphia, for example, where we have 

 the European species Tetragnatha extensa; and along the margins of our 

 ponds and waters are seen immense numbers of large examples of the Stilt 

 spider of Hentz, Tetragnatha grallator, which is probably identical witli 

 Tetragnatha elongata of Walckenaer. 



A study of the spider fauna also justifies the inference that the climate 

 of the Tertiary period in Europe was essentially the same as that of 

 Florissant. This is especially strengthened by a view of the recovered 

 insect forms of the two continents.^ Of the insects in amber Mr. Hope 



\ 



Fig. 372. The fossil spider Nephila pennatipes. 

 (After Scudder.) 



' Ter. Ins. N. A., page 77. 



^ Recherches sur les Insectes Fossiles des Tei-rains Tertiaires dp la Fi-ance. 

 Uiisitalet, pages and .'58. Bibliotheque de TEuole des Hautes Etudes, 1874. 



Par M. 



