ON SOME OF THE FOSSIL TETTIGID^* 181 



Again, " M. Mariette has found barley in the graves of 

 Sackhara of the fifth dynasty, 5400 years old," in no 

 wise dilfering from our own. Such considerations 

 confirm the established axiom that for us, at least, as 

 workers in modern biology, species must be dealt with 

 as fixed quantities. 



A priori considerations might make the occupation 

 of constructing a phylogenetic tree of Homoptera 

 seductive, and perhaps interesting, as showing 

 possible lines of descent ; but the pitfalls are too 

 numerous to allow of any attempt to be made here or 

 elsewhere, from the want of adequate materials. 



Tettigid.e in Amber, and Description op Plate G. 



On Plate G, I have relied for typical examples, 

 almost exclusively, on Germar and Berendt's fine 

 illustrations of the Cicada enclosed in amber. Of 

 these I have chosen, for the present purpose, only a 

 few species out of several dozen insects engraved on 

 their excellent plates, and these few only because they 

 seem suited for a comparison with recent British forms. 

 Amber specimens have an obvious advantage over 

 fossils, from the character of the matrix. The insects 

 are presented in a less fragmentary condition, and 

 such fine details as hairs and setae on the limbs are 

 well shown when present. 



Fig. 19. Cixius testudinarius, Germ, and Ber. This 

 must have been a handsome insect, with its pointed 

 vertex and elaborate neuration. The pygofer appears 

 to be very simple. The elytron is furnished with a 

 continuous subapical border, and the apex is cut into 

 perhaps twenty small distinctive cellules. The wing- 

 neuration, also, is complex. The nervures are not 

 spotted with setigerous granules, as we see commonly 

 in recent Cixiidse. 



Fig. 20. Cixius insignis, Germ, and Ber., varies 

 much from C. testudinarius, both as being smaller, 



