416 C. R. Osten Sachen: AntocTia O. S. a*nd Orimargula Mih. 



and is hardly perceptible under a streng lens. Under a power of 

 150 tlie wing of A. opalizans appeared very densely and minutely 

 dotted; tlie hairs originating from these dots were imperceptible and 

 could be discerned in certain places only, where a fold allowed a 

 side-view. Under the same power, and under much lower powers, 

 the wängs of Thaumastoptera showed the hairs most distinctly, 

 issuing from dots much more sparsely scattered than those in An- 

 toclia. The same experiment was tried with a wing of Dicrauoptycha, 

 also remarkable for its fine pubescence (1. c. p. 117), with the same 

 result: this pubescence proved to be much coarser than that of 

 AntocJia. On the contrary, the wing of Orimargula subjected to 

 the same test and placed under the microscope alongside of the wing 

 of Antocha, showed exactly the same rainuteness of pubescence, to 

 which the peculiar opalescence which distinguishes both species is 

 probably due. This fact I think Clinches the argnment of the generic 

 iflentity of Antocha opalizans and Orimargula alpigena. 



The general result of this examination may be formulated thus: 

 besides a general agreement of characters, as befits two species of 

 the same genus, these species have two particular characters 

 in common, which bind them still closer and distinguish them from 

 the majority of Limnobina: first, the unusual, but only apparent, 

 glabrousness of the wings, produced by the extreme minuteness and 

 density of the microscopic pubescence, and second, the convergence 

 of the auxiliary and the first longitudinal veins. That in A. opali- 

 zans the discal cell is closed and in alpigena open, does not con- 

 stitute a generic difference; in several genera among the Limnobina 

 both forms occur in diiferent species {Dicranomyia, EUiptera etc.). 

 I will notice in this connection that in constructing his dichotomic 

 table of the Limnobina an o mala (1. c. p. 199) Prof. Mik has over- 

 looked the fact that EUiptera clausa 0. S. from California has a 

 closed discal cell and not an open one, like the european Ellijdera 

 omissa. This table, as much as mine in Monogr. etc. IV, p. 46 

 require amending in regard to the genera Antocha and EUiptera 

 in both of which the discal cell is sometimes open. 



Antocka, from the peculiarity of its characters, seems to be, like 

 most of the Limnobina an o mala, a survival of an earlier fauna. 

 Such genera are for the most part not rieh in species, and offen 

 monotypical. The discovery of a second species of Antocha is there- 

 fore an interesting fact, more interesting than the hasty creation of 

 a dubious, new genus. 



