ANCESTRAL SPIDERS AND THEIR HABITS. 



459 



VI. 



The fragile nature of the spider's spinningwork has passed into a prov- 

 erb expressive of utter weakness and ephemeral age. Yet Mr. Scudder has 

 uncovered for us a fossil cocoon, about one-fifth of an inch long, 

 that dates from the distant period of the Oligocene, and which 

 , he describes under the name of Aranea columbise. 1 This co- 



coon has been found at widely separated points Florissant, Green 

 River, Wyoming, and British Columbia and thus appears to have had 

 some favored environment or especial qualities inducing preservation. One 

 might suppose that the large cocoons of Orbweavers, especially those with 

 tough encasements, like Argiope and Cyrtarachne, or the large flossy silken 

 ball of Nephila, might easily have been fossilized under circumstances that 

 allowed the preservation of the araneads themselves. None of these, how- 

 ever, have yet been discovered, and the little Aranea columbise cocoons 

 are the sole representatives of the spinningwork of the aranead weavers 

 of the Tertiary. Eleven of these in all have been found, and the survival 

 of this minute bit of cocooning spinningwork is so interesting and im- 

 portant that I give a full abstract of Scudder's description thereof. 2 



Among the stones obtained by Dr. George M. Dawson in British Co- 

 lumbia are several containing the flattened remains of the egg cocoons of 

 spiders. There are no less 



than eight of them, occurring 

 Cocoons. , 



by pairs, none of them re- 

 verses of others. They vary slightly in 

 size, and more in shape, owing, no 

 doubt, to their varying position when 

 crushed ; probably they were globular, 

 or possibly slightly oval in shape; av- 

 eraging about five millimetres in the 

 longer and four millimetres in the short- 

 er diameter ; of a firm structure ; testa- 

 ceous in color, and hung by a slender 

 thread, less or much less than quarter 

 the length of the egg cocoon (averag- 

 ing, perhaps, one millimetre in length), to a thickened mass of web, at- 

 tached to some object or to the mother's web. 



That they have been preserved by pairs upon the stones has no signifi- 

 cance, and, indeed, may be due simply to the way the stones were broken, 

 for they lie at varying distances apart, with no sign of connection, and 

 placed with no definite relations to each other. 3 Two of them show no 



FIG. 387. FIG. 388. 



The fossil spider cocoon, Aranea Columbia. 



FIG. 387. With the pedicle by which it was 

 suspended. FIG. 388. Much elongated by 

 pressure. Both figures are enlarged be- 

 tween five and six times. (After Scudder.) 



1 First described in the Report of the Geological Survey of Canada for 1876-77, pages 

 463, 464. 2 See Tertiary Insects of N. A. 



3 Many spiders make two or more cocoons, which sufficiently accounts for the above fact. 



