Vol. XXviii] ENTOMOLOGICAL NEWS I7I 



of an encumbered terminology, however, but a doubt as to 

 real homologies of the vein that kept me from doing something 

 like this earlier. I found that the anal trachea originates in 

 the position of the straight adult vein, and only later in de- 

 velopment moves up against the cubital, becoming twice angu- 

 latcd. I found the extreme base of the wing saclike and open, 

 its membranes tardily fusing to delimit the vein cavities ; and 

 it was easy to conceive that a small marginal trachea, like the 

 anal, occupying a constricted place at the base of the wing 

 might have slipped over where there was obviously more room ; 

 and there was and is much doubt in my mind as to whether 

 the vein ever went along with the trachea. This doubt was not 

 resolved by reading Tillyard's paper, for he brings in no new 

 evidence whatever, and I have not his confidence in the con- 

 stancy of the tracheae. However, Professor Comstock, on 

 reading his paper, set about it and found some new evidence. 

 He reasoned that if the base of the so-called anal vein be a 

 secondary development, some fossil form, if primitive enough, 

 might show its absence. At once he found a single figure of a 

 fossil Acschna Uasdna of Brodie, which shows this condition. 

 At least the drawing as oft'ered by Brodie^ and copied by Hand- 

 lirsch'^ shows it. In other parts of the wing, however, this 

 drawing shows obvious inaccuracies. Wherefore. I desired to 

 have the facts confirmed; so I wrote Mr. Herbert Campion to 

 request a re-examination of the specimen. He wrote at once 

 that he though it was in the Warwick Museum, but on the 

 13th of May, 1916, he wrote again that it could not be found. 

 Assuming the correctness of this detail of the figure, the best 

 evidence now available seems, therefore, to be in favor of 

 Tillyard's interpretation. 



Tillyard's interpretation of the radial sector of the Zygop- 

 tera di fibers utterly and irreconcilably from my own. He 

 found, as I did earlier, that the trachea corresponding to the 

 radial sector is not attached to the radial trachea in any of the 

 Zygoptera, but appears as an added branch of the median tra- 



*Brodie. Fossil Insects of the secondary rocks of England, PI. 10, 

 Fig. 4. 



"Handlirsch. Die fossile Insecten, PI. 42, Fig. i. 



