VIII FOSSIL FORMS — CLASSIFICATION 543 



mian fossil, was formerly supposed to be a Homopterous Insect, 

 but it is very anomalous, and its claim to a position in Hemip- 

 tera is denied by Braner,^ who considers it to be Orthopterons. 

 It is now generally recognised that this fossil requires complete 

 reconsideration. Another Permian fossil, Fulgorina, is admitted 

 to be Homopterous by Scudder, Brauer and Brongniart. Scudder 

 thinks the Carboniferous Fhthanocoo'is was an Archaic Hetero- 

 pterous Insect, and if correct this would demonstrate that both of 

 the two great Sub-Orders of Hemiptera existed in Palaeozoic times. 

 Brauer, however, is inclined to refer this fossil to Homoptera, and 

 Brongniart " speaks of it as being without doubt a Pulgorid. 

 Dictyocicada, Ehqndiojytera and 3Icganostoma, from the Carboni- 

 ferous shales of Commentry, have also been referred to Fulgoridae 

 by Brongniart, but the evidence of their alliance with this group 

 is far from satisfactory. In the Secondary epoch numerous 

 Hemiptera existed, and are referred to several of the existing 

 families. They come chiefly from the Oolite. In the Eocene of 

 the Isle of Wight a fossil has been discovered that is referred to 

 the existing Homopterous genus Triecphora. 



We are not entitled to conclude more from these facts than 

 that Homoptera probably appeared before Heteroptera, and date 

 back as far as the Carboniferous epoch. 



Classification and families. — No complete catalogue of 

 Hemiptera exists, but one by M. Severin is in course of publica- 

 tion. It is probable that there are about 18,000 species at 

 present described, two-thirds of this number being Heteroptera. 

 In Britain we have about 430 species of Heteroptera and 600 

 of Homoptera. The classification of the Order is not in a very 

 advanced condition. The following table exhibits the views of 

 Schiodte ^ in a modified form : — 



Front of head not touching the coxae. I. Heteroptera. 



Front of head much inflexed so as to be in contact -with the coxae. 



II. Homoptera. 



Sub-Order I. Heteroptera. 



Posterior coxae nearly globose, partly embedded in cavities, and having 

 a rotatory movement. Mostly terrestrial forms. 1 . Trochalopoda. 



Posterior coxae not globose, larger, and not embedded ; their articulation 

 with sternum almost hinge-like. Posterior aspect of hind femur usually 



1 SB. Ak. JFien. xci. 1 Abth., 1885, p. 275. 

 - Lcs Inscctes jossiles, etc., 1894, p. 452. * Ann. Nat. Hist. (4) vi. 1S70, p. 225. 



