184 BRITISH CICADA. 



Cicada, does not necessarily remove it from the 

 Homoptera. 



As such authorities as Butler, Westwood, Bates and 

 others are against its Homopterous type, I do not 

 press more than what I have said on page 176 of this 

 volume. 



The stratum there mentioned is improperly called 

 Stonesfield slate. The rock has a structure sufficiently 

 laminated to allow of its use for roofing purposes ; but 

 its composition is in no wise that of a slate. 



It is remarkable, and it forms one of the problems 

 in Palaeontology, that we find certain ancieut insects 

 which seem to combine structural features, which now 

 are the characteristics of separate modern groups ; and 

 side by side with these, "we have the apparition of 

 modern types," which make a consistent natural 

 classification very difficult. 



]Vo7'ks consulted tvith reference to Fossil Insects. 



Brodie, P. B. ' History of the Fossil Insects in the Tertiary Eocks of 



England,' with notes by J. 0. AVestwood. 1845. 

 Butler, A. G. ' On the Oldest Fossil Butterfly. PalcBontina oolitica.' 



1873. 

 Germar and Berendt. ' Or'ganische Keste im Bernstein,' &c., with notes 



by H. A. Hagen. Berlin, 1856. 

 Goeppert, H. E., and G. C. Berendt. ' Die Bernstein.' 1845. 

 Goss, H. ' The Geological Antiquity of Insects.' 8vo. 1880. 

 Heer, Oswald. ' Die Urwelt der Schweitz.' Translated by Dallas and 



edited by Heywood. 1876. 

 Oppenheim, P. " On Palseontina, and Jru-assic fossil insects," &c. ' Neue 



Jahrb.' vol. i. pp. 40—57. 1891. 

 Scudder, S. W. ' Early Types of Insects.' 1879. 



' The Tertiary Lake-basin of Florissant.' Washington, 1881. 



' Systematische Oversicht der Fossilen Insecten,' with figures. 



Miinchen, 1886, 



' Sj'stematic Eeview of our Knowledge of Fossil Insects.' 



U. S. Geol. Survey. Washington, 1886. 



' Tertiary Insects of North America,' vol. xiii. U. S. Geol. 



Survey, 1890. 



Canadian Fossil Insects — Tertiary Hemiptera,' vol. ii. Geol. 



Survey of Canada. 



