558 THE PANORPOID COMPLEX, iii., 



shows that it is very strongly formed, and exactly resembles the 

 other main veins near the base of the wing. All the true cross- 

 veins are very weakly formed, and their impressions in the fossil 

 are of quite a different type and intensity. 



(b) As regards its direction, this is oblique, and concave to 

 the base of the wing, i.e. exactly similar to that of the lower 

 arm of the Y-vein, but on the other side of the axis of symmetry 

 of the Y. We know for certain that the lower arm of the Y is 

 Ciii. and not a cross-vein; there can, therefore, be no reason 

 (outside of a bias present from a previous belief that the vein 

 corresponding to the upper arm of the Y in other Orders is a 

 cross-vein) why it could possibly be regarded as such in the 

 Paramecoptera . In other words, if the wing of Belmontia bad 

 been an absolutely new type, with no close relatives amongst 

 existing Orders, nobody would have suggested that the upper 

 arm of the Y was a cross-vein. 



(c) As regards its connection with the main stem of the Y- 

 vein, this is even more direct and complete than is that of Cuj. 

 This can be well seen from the photograph in Plate xxxi., fig. 35. 

 Anybody who might be asked, with an unbiassed mind, to say 

 which of the two arms of the Y-vein is most likely to be a cross- 

 vein, assuming that one or the other of them must be such, would 

 certainly indicate the lower arm, i.e. Cuj from a study of its 

 method of connection with the main stem. 



(d) As regards the presence or absence of macrotrichia, this 

 vein is most certainly part of a main vein. An examination of 

 any one of the main veins in this fossil will show the sockets 

 of macrotrichia clearly present, whereas no such structures can 

 be seen upon any of the cross-veins. Several of these can be 

 seen upon the lower arm of the Y, i.e. Cu 1# Although the 

 upper two-fifths of the upper arm of the Y is somewhat dam- 

 aged, and not well preserved, yet two sockets can be clearly 

 seen upon the lower three-fifths, thus proving that it carried 

 macrotrichia, and must therefore have been a portion of a main 

 vein. In Plate xxxi., fig. 16, the arrow points to one of the 

 sockets on My while another on Ciij can be seen by following 

 the stem of the arrow backwards. 



(e) As regards the alternate convexity and concavity of the 

 main veins, the fossil shows quite clearly that R and Cu are 

 convex, M concave. Further distad, as in all Panorpoid wings 

 in whicli the levels of these veins differ appreciably, M 1+2 



