BY R. J. TILLYARD. 



741 



that the resulting vein has been labelled Cuj without any hesita- 

 tion, for the deception is almost as complete as Nature could 

 possibly have made it, and the oblique vein is the only clue left 

 to the discovery of this remarkable venational freak. 



We see, therefore, that in the forewiiig of Myrmeleonidce, the 

 media is really two-branched, and that the vein usually called 

 the "upper branch of the cubitus" and labelled Cuj, is really a 

 composite vein, formed proximally — for the short distance from 

 the cubital fork to the foot of the oblique vein — by Cuj, and 

 thence distad by M^. I propose, therefore, to name it the 

 cuhito-mediaii vein, with the notation Cui-I-Mo. As far as I 

 know,- there is no exact homologue to this vein in any other 

 group of insects. 



La, 



M,M, 



Text-fig.6. — Forewing of M. unineriatus ( x 3), to show the correct naming 

 of veins. (Original). 



(3). Some alteration of our ideas as to the extent of the cubitus 

 is necessary. In the tracheation, the main stem of Cu is con- 

 tinued on, with only a slight downward bend, by Cug as a fairly 

 stout trachea giving off four or five descending branches. By 

 contrast, Cuj is a very weak trachea running obliquely upwards 

 to fuse with the much stouter Mo. It is possible that the first 

 of the branches descending from Mo may be the cut-off end of 

 Cui. But, as this cannot be definitely shown to be the case in 

 our photographs (though perhaps it might be seen in figures from 

 a larger species), we must, for the present, limit Cui to the short 

 piece between the cubital fork and the foot of the oblique vein. 



