1913] The Wing Venation of the Jassidce 105 



This paper is founded upon the work of Comstock and 

 Needham '98-'99. It adopts the same system they propose for 

 naming the veins and for naming and numbering the cells, as 

 the writer believes that this system is the only logical one that 

 has been offered. An attempt made to homologize the veins 

 of adult Homoptera and a subsequent study of the tracheation 

 that precedes venation, has thoroughly convinced the writer 

 that the Comstock-Needham system is the only logical one. 



THE FORE WING. 



The type of the fore wing of Jassidce is fairly uniform but in 

 order to point out the difference that exists the tracheae will be 

 considered in detail beginning at the costal margin. 



The wings of Jassidce show marked specialization by reduc- 

 tion. This reduction is usually accompanied by the atrophy 

 of one of the branches of one of the main tracheae and the shifting 

 of a branch of a neighboring trachea until it occupies the region 

 of the atrophied trachea. This is well illustrated in the atrophy 

 of Mi+2 of the fore wing which is discussed below. Another 

 excellent example of the same thing is found in the Typhlocy- 

 bidce where M3+4 occupies the region usually traversed by Cui. 

 The atrophy of these trachese with the subsequent shifting of 

 other tracheae which take their places gives to the wings of the 

 Jassidce their characteristic aspect. 



THE COSTA OF FORE WING. 



The costal trachea is absent in all of the Jassid wings that 

 have been examined with the exception of Gypona (Fig. 8). 

 Here the costal trachea is long being almost as long as subcosta 

 and running parallel with it throughout its length. In no other 

 Jassid was any trace of Costa found. In all cases the nymphal 

 pad was removed as near the base as possible and the body 

 trachea was examined for traces of the costal spur but no trace 

 of such spur was found. This was due to the fact, perhaps, that 

 it is impossible to get any great length of the body trachea in 

 such a dissection. In a few cases, however, a considerable 

 length of the body trachea was secured (Figs. 3, 5, 62, 64). 

 This indicates that Costa has practically disappeared from 

 the Jassidce. 



