THE FOSSIL FAUNA AND FLORA OF THE 

 FLORISSANT (COLORADO) SHALES 



By T. D. a. Cockerell 



The Tertiary lake basin of Florissant, Colo., is one of the most 

 famous localities for fossils in the world. The plants and insects of 

 a past age are wonderfully preserved in fine volcanic sand or ash, 

 deposited in layers which readily spHt apart, reveahng the specimens, 

 just as they fell, in prodigious numbers. Green leaves and even branch- 

 lets were torn from the trees, and insects perished wholesale, in a catas- 

 trophe which must have equaled that of Martinique. There were, in 

 fact, several successive eruptions, as about a dozen different horizons 

 are found to be fossiliferous. While some of these may represent 

 a single period of volcanic activity, it is not to be doubted that consider- 

 able periods elapsed between some of the deposits. Perhaps the non- 

 fossihferous shales were deposited so soon after the fossiliferous ones 

 that no Hving creatures remained to be entombed, all having been 

 destroyed or driven away; in this case the next fossil-bearing layer 

 will indicate a new eruption, following after a greater or less lapse 

 of time. 



In all eleven vertebrates, one mollusc, 6io insects, 30 spiders, and 

 about 145 recognizable plants have been described from these beds. 

 The insects were all described by Mr. S. H. Scudder, except a few 

 plant-Uce named by Mr. Buckton from dravrings supplied by Mr. 

 Scudder, and some hymenoptera recently examined by the present 

 writer. The Scudder collection, at the Museum of Comparative 

 Zoology, Cambridge, Mass., contains probably at least another 400 

 species of insects. These were to have been described by Mr. Scud- 

 der, but he is no longer able to work upon them, and others will be 

 obUged to do the best they can in the absence of the master hand. Mr. 

 Samuel Henshaw, curator of the Museum of Comparative Zoology, 

 has very kindly transmitted to me the bees and wasps for study, and 

 the work on them is already completed. 



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