ANCESTRAL SPIDERS AND THEIR HABITS. 449 



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

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



^^ , . rupted at intervals by the influx of new lava flows, or the burv- 

 Volcanic • /■ ji 1 ., ,. , , , ■' 



Showers. ^"^ bottom sediments beneath heavy showers of volcanic 



ashes.' Tliat many insects 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 season must have added contributions to tlie im- 

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

 They may 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 tlie 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- 



Spiders. ^'^^'* species have been uncovered, of which one, Epeira molas- 

 sica Heer, is an Orbweaver.''^ These fossils are, for the most 

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

 M'idely represented among living fauna. Eleven species are figured but 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 tliose 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 larvaj, 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 tlie 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 Mi.ssissippi. The general asi)ect of 

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

 that visited them, like the spiders that made them their prey, must have 

 given a familiar face to the scenery. 



' Palcon. Floris.sant, page 298. 



2 Tlie Primeval World of Switzerland. By Professor Heer. Hcvwood's English transla- 

 tion, Vol. II., |)age 10, 1876. 



