FROG-HOPPERS AND PLANT-LICE. 601 



The Jassidce differ from the Cercopidoe, in the hind tibiae having a row of 

 spines below. They are small yellowish insects, most of 

 which are placed by Mr. G. B. Buckton, in his " Monograph Family Jassidce. 

 of the British Cicadce," under the genus Deltocephalus (Burin.). 



The Membracidce are remarkable for the thorax being produced into a long 

 horn or spine, which is frequently recurved over the abdomen. The genus 

 Centrotus (Fabr.), represented in England by C. cornutus 

 (Linn.), is very numerous in species, which are generally of a Family 



black or brown colour, with paler wings and tegmina, the Membracidce. 

 sides of the thorax projecting to a more or less sharp point, 

 and a long spine, broad at the base, and narrowing behind, projecting from 

 the thorax over the back. They are insects of small size, rarely reaching a 

 quarter of an inch in length. Among the foreign species, the forms of the 

 horn in this family are frequently very remarkable. In 

 one genus, Umbonia (Burm.), the species are yellow, 

 streaked with red, and the whole insect is shaped exactly 

 like the thorn of a rose tree. These are found in Tropical 

 America. Respecting the North American species, Prof. 

 Comstock remarks, "In some cases the prothorax is elevated 

 above the head, so that it looks like a peaked nightcap ; in 

 others it is shaped like a Tam-o'-Shanter ; and sometimes F . 

 it has horns, one on each side, which have given one species l9 ' comutus 

 the name of the buffalo tree-hopper." In others, again, Nat. size! 



the horn of the prothorax is nearly vertical, larger than 

 the whole of the rest of the insect, and recurved and bifid at the extremity, 

 and in some species from tropical America, belonging to the genus Bocydium 

 (Latr.), the horn separates into a number of little balls, each of which again 

 throws off a small spine. 



The remaining families of Homoptera which we have to notice are all 

 plant-feeding insects of small size, in which the proboscis appears to issue 

 from between the front-legs, if present at all. The antennae, when present, 

 are usually long and slender, and the tarsi are one or two- jointed. 



The Psyllidce are short, broad insects, which have been compared to 

 minute Cicadas. The hind legs are thickened, and the antennae terminate in 

 two bristles. They leap about on plants, and many of the 

 species produce galls. They resemble the Aphidw in dis- Family 



charging a sweet fluid, which attracts ants, and their larvae Psyllidce. 

 are covered with a white cottony exudation. They are pro- 

 vided with three ocelli. The wings are transparent. 



The Aphididce, which are often called plant-lice, smother-flies, or blight, 

 have slender legs, not fitted for leaping ; the antennae are long and slender, 

 not terminating in a double bristle ; the ocelli are absent, 

 and the wings are transparent. There is a most curious Family 



alternation of broods in these insects, some forms being Aphididce. 

 winged, and with separate sexes, and others winged or Plant-Lice, 

 apterous, and capable of producing their kind for an indefinite 

 number of generations before a sexual brood is again developed. Some pro- 

 duce galls, but the greater part feed on the leaves of trees. Sometimes one 

 generation will live on one tree, and the next migrate to another, a future 

 generation returning to the original food-plant. In fact, the anomalies of 

 these insects are endless, and it would require volumes to epitomise even the 

 comparatively little which has already been discovered with reference to their 



