146 BRITISH CICAD.I:, 



the body is matured before the re-productive organs are 

 completed, and thus these last remain but half de- 

 veloped. Some writers have further asserted, and 

 some denied, that the greater or less predominance of 

 a sex in a brood is governed by the character and the 

 amount of nourishment assimilated by the larvae. 

 Such a cause cannot, however, be thought adequate 

 to explain the marked paucity of males in some 

 Hemiptera, as we find to be the fact in the Coccidae, 

 the Aphididse, and, to a less degree, in the Tettigidae. 



Synoptic Table of the Genus Typhlocyba. 



As an assistance to the preliminary grouping of 

 species, the following sketch has been made upon a 

 naked-eye view of the same. The most easily recog- 

 nized insects are placed first in this list : — 



Typhlocyha quercus.- — Known by its blood-red, but 

 not always similarly grouped, blotches. 



T. nitidula. — Elytra nearly white : when closed, two 

 dark transverse bands are to be seen ; one below the 

 scutellum, while the other crosses the midst of the 

 elytra. 



(T. Norgueti is a variety, with more confluent bands.) 



T. geometrica. — Each elytron has a long, thin, black 

 longitudinal streak near the suture. 



T. jiicunda. — The largest British insect of the genus. 

 Body black. Elytra pale umber-brown. 



T. sexpunctata. — Elytra more brindled than other 

 species. Elytron, when closed, shows three obscure, 

 broad, brown transverse bands. A black streak occurs 

 on the occiput. 



All the remaining species have pale elytra, and are 

 not very easily separated by the naked eye : — 



T. dehilis. — Abdomen black. Elytra with fuscous tips. 

 T. cuirovittatus. — Elytra more or less golden-yellow. 

 Abdomen black. 



