99 



to Dr. Mantell, almost wholly composed of these cases, 

 cemented together by Calcareo Siliceous matter into stone, which 

 is much employed for building purposes. 



" If we consider," says Mr. Scrope, " that strata of five 

 or six feet in thickness almost entirelj'- composed of these tubes 

 (cases) once extended over a district presenting a surface of many 

 hundred square miles, we may have some idea of the countless 

 myriads of minute beings which lived and died Avithin the bosom 

 of that ancient lake." 



Professor Pictet seems to entertain some doubt as to whether 

 the tubes or cases before mentioned, of Avhich the indusial lime- 

 stone is in a great measure composed, were formed by larv?e of 

 I'hryganea or Caddis worms. He says these tubes are much 

 thicker than those formed by Phryganea ; the internal cavity is 

 much smaller, and they are besides much longer, and more 

 resemble the tubes formed by certain Annelida. 



M. Oustalet has recently made a special study of the fossil 

 insect fiiuna of Auvergne, and has published on the subject a 

 most important memoir, only equalled, in my opinion, in 

 value by Professor Heer's great work on the insect fauna 

 of CEningen ami Radoboj. 



The places in this part of France in which the majority of 

 these fossils have been discovered are Corent, Menat, and St. 

 ( f erand le Puy. From these localities M. Oustalet states that he 

 lias studied not less than one hundred specimens in the collections 

 of M. M. Lecoq and Fouilhoux, and the Museum of Natural 

 History at Paris, or collected by himself during his travels in 

 Auvergne. 



These specimens comprise some forty-nine species distributed 

 amongst the following orders in the following manner, viz. : — 



Coleoptera 10 species. 



Orthoptera ... ... ... 1 ,, 



Neuroptera 5 ,, 



Hymenoptera ... ... ... 2 ,, 



Diptera ... ... ... ... 30 ,, 



Lepidoptera 1 ,, 



49 



