450 AMERICAN SPIDKRS AND THEIR SPINNINGWORK. 



III. 



The climatic conditions under which the Florissant spiders lived and 



died are established by a testimony which is quite accordant, both from 



the fossil flora and fauna. According to Lesquereux, the plants 



Climatic i nc [i ca te a climate like that of the northern shores of the Gulf 



of Mexico at the present epoch, and have a general aspect which 



recalls that of the vegetation of uplands or valleys of mountains. 



The fishes, according to Professor Cope (quoted by Scudder), indicate a 



climate like that at present found in latitude thirty-five degrees in the 



United States. 



Professor Scudder thinks that the insects from their general ensemble 

 prove a somewhat warmer climate. He refers especially to the presence of 

 a great number of white ants imbedded in the shales, a testimony that is con- 

 firmed by a study of other insects, which are found to be largely tropical or 

 subtropical in their nature. 1 In a subsequent brief and interesting review 

 of the Florissant spiders, and comparison with those from the European 

 beds, 2 Mr. Scudder - repeats this opinion. He considers that the present 

 distribution of the allies of the fossil spiders points to a climate like that 

 of the middle zone of our Southern States, or the two shores of the 

 Mediterranean in Europe. However, of the genera which he cites in proof 

 of this, only one, Nephila, seems to me in point. This spider is undoubt- 

 edly tropical. I have a number of species from Africa, Zululand, Mada- 

 gascar, Liberia, etc., where they have an enormous development. 



Our Gulf States have one species, Nephila plumipes, which is abundant 

 in many parts thereof, and is even more characteristic of the spider fauna of 

 Central America and the West Indies. As it has never yet been found 

 in the United States outside the southern belt of the Southern States, the 

 presence of a closely related species in the Florissant shales would 

 seem to be conclusive as to the nature of the climate during the 

 period at which their fossils were imbedded. The specimen pub- 

 lished by Professor Scudder, which I reproduce (Fig. 372), is well enough 

 preserved to prevent any doubt as to its generic identity. 



According to Scudder 3 it is a much smaller species than Nephila plu- 

 mipes Koch, if the fossil be fully grown, and differs from 'it in some 

 striking points. The eyes differ considerably, although the position of only 

 two of those of the fossil species is known. The corselet is squarer in the 

 fossil, and per contra the abdomen is oval and not quadrate, while the tarsi 

 are unusually long in proportion to the whole leg. The tufts of hairs occur 

 only on the extremity of the tibia. I have not seen the fossil, but judging 



1 Paleontology of Florissant, page -!H>. 



2 Fossil Spiders, Harvard University Bulletin, No. 21, page :>u:> : set- also Tertiary Insect", 

 page 51. 



3 Tertiary Insects of North America, page 90, pi. xi., Fig. 12. 



