MIOCENE APHIDES OP AMERICA. 173 



poplar has been beautifully preserved, showing very 

 distinctly its principal ribs and neuration. The swell- 

 ing is placed at the juncture of the foot-stalk, "just 

 as we see it with our Pemphigus bwrsarius." The gall 

 has several rib-like corrugations. A similar gall 

 formed on the leaf of Popidus transversa, A. Br., was 

 noted by Prof. Heer in the collection of Herr Lavater. 

 In the (Eningen specimen a small speck appears which 

 is club-shaped, and possibly is the work of some gall- 

 making gnat like the Gecidomyia populnea (popidea ?) 

 of Schrank. 



Two traces of legs (Beinreste), probably belonging 

 to an Aphis, are observable in proximity to this leaf. 



Size of the gall 3x| lines. 



4.— OBSERVATIONS ON THE ANCIENT APHIDES DEPO- 

 SITED IN THE TERTIARY BEDS OF NORTH AMERICA, 

 AS EXEMPLIFIED BY SOME OF THEIR FOSSIL RE- 

 MAINS FOUND IN THE FLORISSANT BASIN OF 

 COLORADO. 



Some interest and also surprise is raised at the com- 

 paratively perfect condition of the impressions left by 

 these insects in strata, which must have been once a 

 soft mud and must have settled down rapidly. There 

 are nineteen separate figures already drawn in prepa- 

 ration for Mr. S. H. Scudder's fine contribution 

 to our knowledge of Fossil Insects, shortly to be pub- 

 lished in connection with the United States Govern- 

 ment Survey of the Territories of North America. 



These figures leave no doubt as to what family of 

 insects they ought to be referred. The delicate an- 

 tennae, as might have been anticipated, have in great 

 measure failed to leave such characters as would have 

 surely pointed to recent genera ; but in the figures of 

 the plates above referred to, these organs, as drawn 



