MIOCENE APHIDES OP AMEEIOA. 175 



they are very characteristic ; and they prove liOw very 

 persistent these minute Heniiptera have been from 

 early geological time, in their general morphological 

 outlines. 



Figures 4, 5, and 6 are more diverse from recent forms, 

 but still they may be said to be referable to modern 

 genera. ~No lower wings are here represented, though 

 they must certainly have existed. It may be remarked, 

 however, that the lower wings of recent Aphides are 

 more fragile than the upper. Figure 6 has a some- 

 what mixed character, between Pemphigus and 

 Chermes. The large costal cell here is notable, and 

 possibly this and the position of the oblique veins 

 might suggest the construction of a new genus in the 

 classification of fossil Aphides. 



The body of figure 4 has probably undergone pres- 

 sure. The great breadth of the abdomen in the region 

 of the nectaries might suggest a Lachnus ; but, on the 

 other hand, the well-defined wing, with its single fur- 

 cation, starting from the cubitus, which is remarkably 

 stout, would place this insect somewhat more correctly 

 in Schizoneura. 



The pressure on these insects has been so great that 

 the details of both the upper and the lower surfaces can 

 be seen at the same time on the faces of an opaque 

 slab; much in the same manner as a spider may be 

 viewed mounted on a slide for the microscope, after 

 treatment with potash. 



It is remarkable how distinctly the pigmental bands 

 and spots can be traced on some of the bodies of these 

 old Homoptera. One of Mr. Scudder's figures (12) 

 might suggest that a viviparous embryo was enclosed. 

 An examination of the fossils themselves would per- 

 haps show whether parthenogenesis existed at this 

 early era. A substantiation of such a fact would prove 

 of interest, as connected with the early embryology 

 and development of Aphis. 



