104 ENTOMOLOGICAL XL\YS | \\xii, '21- 



margin of the wing were retained, while this portion of Cnl and 

 vein m-cii became straightened out to form a vertical line, a 

 condition very like that exhibited by vein Cul of Fig. 3, would 

 be produced. Similarly, if vein Cn2 of Fig. 5 became more 

 vertical, it would assume the position of the vein labeled Cn2 in 

 Fig. 3. I would not insist on this interpretation of the venation 

 of Fig. 3, however, since the vein labeled Cu2 in Fig. 3, may 

 represent the entire cubitus (Cit) and the vein labeled Cul 

 may represent vein M3+4, while the vein labeled M, may 

 represent vein Ml+2, and the latter view seems to be the more 

 probable one. 



As was mentioned above, the Zorapteron type of venation 

 (Fig. 5) approaches that of the Aphids (Fig. 4) ; and the 

 Homoptera, as well as the Zoraptera and Psocida, resemble 

 the Thysanoptera in many respects. Since these forms are all 

 very closely interrelated (judging from other structures than 

 the wing veins) the condition occurring in one type of wing 

 venation should throw some light upon that occurring in other 

 related forms. I would, therefore, suggest that the basal 

 portion of the vein labeled R, in Figures 3. 5 and 8, may 

 possibly represent Sc+R, rather than R alone, since, in the 

 type of venation shown in Fig. 4, the basal portion of the 

 vein in the corresponding region of the wing evidently repre- 

 sents Sc+R (with which M, Cu and A have also united) 

 rather than R alone. 



(To be continued) 



ABBREVIATIONS. 



The abbreviations commonly employed in the Comstockian system 

 have been used for designating the veins in the text and in figures 1-12 

 as follows: Sc (Subcosta), R (Radius), M (Media), Cu (Cubitus) 

 and A (Anals). The numerals following the letters indicate tin- 

 branches of the veins in question, thus R\ denotes the first branch of 

 radius, etc. Rs denotes the radial sector, tii-cii denotes the medio- 

 cubital cross vein connecting media with cubitus. M + Cii denotes the 

 fusion product of media and cubitus. al is the alatenaculum, or lobe 

 for holding the fore wing above the hind wing when at rest. 



EXPLANATION OF PLATE II. 

 All figures are of the right fore wing alone. 



Fig. 1 Aclothrips nasturii (Thysanopteron), based on figure by Jon< x 

 1912. The dotted cross-veins do not occur in this species, 

 but are found in many other Thysanoptera. 



