59(3 PROCEEDINGS OF THE NATIONAL MUSEUM, 



the basal part of the third anal vein is preserved in every case, but is 

 interrupted at the point where it should join the anastomosis. Ptei^ou h.s 

 (tij)-. 12, c) and BJennocampa (fig. 72) show a slightly later stage in which 

 only the longitudinal part of this vein is preserved, while many genera, 

 as Dlneura (tig. 03), show the complete atrophy of the entire basal part 

 of the third anal, or at most it is represented only l)y a fold. In Pet^- 

 rcyia (fig. 80) there is developed a peculiar spur on the posterior 

 margin of the cell 1st A opposite the free part of M^+C'Ui- 



The greatest reduction of the anal area is reached in the subfamilies 

 Lobocerinte (fig. 82), Pterygophorinre (fig, 81), and Perginas (fig. 84), 

 where all that remains is the simple straight vein. The members of 

 these subfamilies, at least so far as this area is concerned, have reached 

 the condition found in all the higher Hymenoptera. This condition 

 has been reached by a continuation of the anastomosis found in Lahi- 

 ■darge (fig. 78). As was shown above, the petiolate type of cell might 

 be produced by the anastomosis of the basal part of the third anal, 

 while the condition here is produced by anastomosis of both basal and 

 apical parts. It is an interesting fact that the cell on the basal side 

 of the anastomosis is bounded in front by 1st A+2d A and behind by 

 3d A, while the apical half is bounded in front by 1st A and behind by 

 2d A+3d A, so that the resulting vein is a combination of all three 

 anal veins, which has certainly been brought about in a very round- 

 about manner. 



The second method of the modification of the anal area, namel}^, b}^ 

 the gradual shortening of the free part of 2d A and the almost com- 

 plete obliteration of the emargination of the 3d A is found only in the 

 subfamilies Lycaotinte (fig. 12, /"), Tenthredininse (fig. 12, d-e), and 

 Cimbicinffi (fig. 12, g). When the wings of Itycorsia (fig. 40), Lyda 

 (fig. 37), Csunolyda (fig. 38), Eriocampa (fig. 47), and Strongylogaxtei' 

 (fig. 51) are carefull}^ examined there will be found at the base of the 

 emargination a prominent shoulder, which is distinctly thickened. 

 This shoulder is present in varying degrees in all those genera where 

 the third anal is emarginate at base, but is especiall}' prominent in the 

 genera named. If, now, we examine the wings of most any member 

 of the subfamily Tenthredinina^, as Macroj>hya (fig. 57), we will tind 

 near the basal side of the anastomosis a slight emargination, and just 

 beyond it a thickening. In this emargination and thickening we find 

 the reason for our conclusions that in these subfamilies the contracted 

 type of cells has been produced by a shortening of the free part of the 

 second anal. This conclusion is further confirmed by the great varia- 

 tion in the amount of anastomosis. In the genus .Macrophya alone 

 this condition varies from a well-marked perpendicular free part of 

 the second anal to an anastomosis for some distance. The perpendic- 

 ular free part of the second anal or the anastomosis in the Tenthred- 

 ininic occupies a position nearer the base of the wing than the corre- 



