10 lUinois State Laboratory of Natural History. 



Membracis, so that, transposing the names Tettigonia and Ci- 

 cada, we have a series of genera nearly equivalent to the fami- 

 lies of later systematists. T say nearly, because a few aberrant 

 forms of Jassids (such as Ledra) were included in the Mem- 

 bracida;. A few other genera were established by Fabricius, 

 in his later writings, by the dismemberment of these groups, 

 and subsequent authors have added greatly to the list of genera, 

 so that now as many as two hundred have been proposed, of 

 which perhaps half may stand the test of time. 



STRUCTURE. 



As in all other true insects, the body is composed of a series 

 of more or less irregular chitinous rings, called segments, dis- 

 posed in three regions, the head, thorax, and abdomen. The 

 head in this group is very variable in shape, but always some- 

 what triangular when seen directly from before or from be- 

 hind, the two large and often prominent eyes forming the up- 

 per corners, and the beak arising from the much reflexed apex. 

 The first of the three segments which comprise the thorax is 

 very prominent above, but small and nearly covered by the in- 

 flexion of the head beneath. The other segments are closely 

 connected, and about equal above and below. The abdomen 

 consists of seven or eight segments tapering backwards and 

 provided near the tip with a rather large genital apparatus. 



Head. Returning now to the head, we can distinguish two 

 surfaces besides the backside, which is concealed by the thorax: 

 one above, the dorsal surface, more or less flat; and the other, 

 called the face, often very convex, and including all that por- 

 tion looking downward, forward, and to the sides. These 

 planes are separated by a more or less distinct edge known as 

 the front edge. 



Above the head, between the eyes, and generally surround- 

 ing them, a large variable piece, not very distinctly marked off 

 from the one in front, may be seen, which is known as the ver- 

 tex (PI. I., Fig. 3). The separation from the piece before it, is 

 quite distinct at the sides of the vertex, being by sutures (PI. 

 I., Figs. 1, 2), but often not so at the middle, where it may 

 not be visibly divided at all. 



