ANCESTRAL SPIDERS AND THEIR HABITS. 449 



Scudder thinks that the structure of the rocks indicates a quiet depo- 

 sition of the materials in an unruffled lake through long periods, inter- 

 rupted at intervals l)y tlie influx of new lava flows, or tlie buiy- 



° " ing of the bottom sediments beneath lieavv showers of volcanic 

 Showers. f i mi • i • i i 



aslies.^ ihat many ni sects and spiders were beaten down by 



these showers, destroyed, and buried, is at least probable. Certainly we 



shall not go far astray in picturing such an exigency in the life history 



of the disentombed fossil spiders in our possession. Thus the story of 



Pompeii was enacted among the aranead inhabitants of this upland lake 



shore in the distant Tertiary. 



In this case, every seaison must have added contributions to the im- 

 bedded forms. After the final act of maternity female spiders soon die. 

 They ma}^ often be found, dried up, quite dead, hanging to grass or foli- 

 age, whence they drop off with the leaves. It was not different with the 

 fossils of Lake Florissant; they dropped to the ground and were carried 

 into the water, or dropped directly into the lake, and sank into the muddy 

 sediment, and were buried under the volcanic mud flow. 



By a process somewhat similar the spiders of the Swiss Miocene ap- 

 pear to have been entombed, these soft animals being preserved only in 

 the calcareous marl of the lower Oeningen quarry. Twenty- 

 emngen gjgj^^ species have been uncovered, of which one, Epeira molas- 

 sica Heer, is an Orb weaver.^ These fossils are, for the most 

 part, small, delicate creatures, belonging, with one exception, to genera 

 widely represented among living fauna. Eleven sj^ecies are figured Init not 

 described by Heer, whose figures are repeated by Hey wood. 



Of the insects which fell into the water of the ancient Lake Oeningen, 

 only those have been preserved which were quickly covered by the mud, 

 and thus saved from destruction. Aquatic insects are numerous, and are 

 found in all stages as larvte, pupte, and imagines. Many were so rapidly 

 enveloped by the fine calcareous deposit that they have not merely pro- 

 duced an impression in it, but even the organic substance has been pre- 

 served. By this rapid covering the softest midgets are so admirably pre- 

 served that, under the microscope, the hairs of their legs and wings can be 

 recognized, and the color of the land bugs can still be ascertained. Thus, 

 in Europe as in America, we can picture the local conditions under which 

 the ancient spiders lived as not very different from some of our littoral 

 Atlantic lakes, as Deal Lake, for example, or those of Florida, and the 

 lagoons and bayous of the Southwest Mississippi. The general aspect of 

 the landscape ; the forms and foliage of plants ; the flowers and the insects 

 that visited them, like the spiders that made them their prej', must have 

 given a familiar face to the scenery." 



' Paleon. Florissant, page 208. 



^ Tlio Primeval World of Switzerland. By Professor Heer. Hey wood's English tnuisla- 

 tion, Vol. n., page 10, 1876. 



