276 BULLETIN OF THE 



question here treated — the evolution of this class of insects — is jjos- 

 sible. The facts to be registered for such an advance must be unques- 

 tionable facts, and that is not the case with those stated in this 

 publication. 



"As the simpler Devonian Insects have certain special relations with 

 the Ephemeridte, their description is preceded by an account of the wing 

 structure of the modern Mayflies, as a basis of comparison." (p. 4.) 



The simple fact that none of the fossils has any relation whatsoever 

 to the Ephemerid<e, is a sufficient objection to the descriptions and con- 

 clusions relating to this family. Some exceptions made by the author 

 in the account of the wing-structure of Lachlania and Oligoneuria prove 

 erroneous after a careful examination of the insects. The mediastinal 

 vein is present in Lachlania and Oligoneuria, and the scapular vein ter- 

 minates at the tip in Lachlania. The intercalary vein of Coloburus is 

 to be found also in Ephemerella gibba and in Heptagenia Bellieri. 



Platephemera antiqua. 



The specimen is in excellent condition ; I have before me the type. Fig. 9. 

 This species has nothing whatsoever to do -with the Ephemeridse, and I remark 

 here that my deliberate determination is not based upon a difference of opinion, 

 but merely on the simple evidence of facts. The specimen is a part of the 

 apical lialf, without the tip, of a wing of a gigantic dragonfly. Fig. 10 shows 

 on the hind margin the end of the sector medius, where the margin is often 

 a little retracted. Nearer the tip (in Figs. 9 and 10) the sector nodalis and 

 6ub-nodalis run one near the other, as commonly in dragonflies. No ptero- 

 stigma is visible; but we find it wanting or sometimes slightly indicated in 

 other fossil species. The statement of the author, that " tlie marginal vein 

 runs close to, but does not form, the margin," confirms my determination, 

 as just in Odonata this structure is very common, but not in Ephemerifla;. 

 The conclusion of the author that a general similarity of structure of P. antiqua 

 " with Dictyoneura may be conceded," will not be shared on comparing the 

 figures of the species published by Goldenberg. The existing part of the wing 

 compared with the known fossil species from Solenhofen cannot be larger than 

 about one third of the whole length of the winjj;. To judge from the termi- 

 nation of the sector nodalis, something less than 20 nmi. of the tip are want- 

 ing, much more than is indicated by the outline of the figure. To judge from 

 the distance and the direction of the mediana and the sector nothdis to the base, 

 about 20 mm. must be wanting to the nodus. It w(ndd be the largest known 

 species, the length of the wing about 100 mm. There is no character in the 

 fragment for a closer deternunation except tlu; suddenly narrowed second cubi- 

 tal space ; and this is not mentioned by the author. We luid a similar arrange- 

 ment in Stenophlebia. 



