178 TERTIARY INSECTS OF NORTH AMERICA. 



five were Phryganidfe, and of fifty species described by me twenty-two 

 [44 per cent] belong to this family." Of these sixty-five, moreover, forty 

 were referred to the Hydropsychidse. Hagen, with about seven times as 

 many specimens before him, comes to nearly the same conclusion, for he 

 says that nearly 60 per cent of the specimens of Neuroptera are caddis-flies, 

 and thirty-nine of the eighty-seven species of Neuroptera given in his table, 

 or 45 per cent, are referred to the Trichoptera. 



In this enumeration no account has been taken of tlie occurrence of 

 larval cases of caddis-flies in Tertiary de^DOsits, to which reference was 

 made above. Auvergne has been famous for these which form the so-called 

 indusial limestone deposits, so abundant are they. They were described 

 hy Bosc as long ago as the year XIII (1805) and recently have been dis- 

 tinguished by Oustalet under two distinct names. Hepp also described 

 Phryganea blumii from cases found at Leistadt and Heer P. antiqua from 

 Oeningen. A single one has even been found in amber, with its entombed 

 larva, and Fritsch describes one from the Cretaceous of Bohemia. In this 

 country Dr. Peale discovered similar remains, which I have described as 

 Indusia calculosa. The two fragments of rocks brought home from the lo- 

 cality in Wyoming formed doubtless the floor of a former body of water 

 and are thickly crowded with cases lying in every direction. It is very 

 probable that at least those described here and by Bosc and Oustalet be- 

 long to the Limnophilidge. That in the abundant fauna found in the lake 

 basin of Florissant, including, as we see, a large number of caddis-flies, not 

 a single larval case should have yet been found seems a little remarkable, 

 and the more so since not a few belong to groups, the larvae of which are 

 known to prefer standing to running water. It is hardly to be believed 

 that the streams in the neighborhood of this ancient lake abounded in the 

 larvfe of caddis-flies, while tlie waters of the lake itself were destitute of 

 them. It should be remembered, however (1), that the species which con 

 struct cases of conspicuous size out of hard matei'ials mostly belong to the 

 Limnophilidfe, of which Florissant furnishes but one species ; (2), that the 

 larvae of the prevailing group, Hydropsychidae, more commonly inhabit 

 running water, and that their cases are made of grains of stone affixed to 

 larger stones ; (3), that the bottom of the lake in which the insect deposits 

 occur nowhere has shown, as for as I have seen, any sign of stones large 

 enough to have sei-ved as a basis for the attachment of the smaller grains 



