INTRODUCTION. 37 



3 N. Am. sp.); Bhamphidia (2 Eur., 1 N". Am. sp.); Dicranoji- 

 tijcha (2 Eur., 3 N. Am. sp.); Antocha (1 Eur., 1 N. Am. sp.); 

 Trimicra (2 or 3? Eur., 1 N. Am. sp.); Syiivplecta (3 Eur., 1 

 N. Am. sp.); Goniomyia (5 or 6 Eur., 4 N. Am. sp.) ; Empeda 

 (4 Eur., 1 N. Am. sp.) ; Cliionea (2 Eur., 2 N. Am. sp.) ; Epi- 

 phragma (I Eur., 2 N. Am. sp.) ; Trichocera (5 Eur., 4 or 5 

 N. Am. sp.); Anisomera (8 Eur., 1 I^. Am. sp.) ; Penthoptera 

 (2 Eur., 1 N. Am. sp.) ; Amalopis (about 8 or 9 Eur., ,5 N. Am. 

 sp. ) ; Dicranota (about 5 Eur., 2 N. Am. sp.) ; Pedicia (1 Eur., 

 1 X. Am. sp.); Ula (2 Eur., 2 N. Am. sp.); Cylindrotoma (2 

 Eur., 2 N. Am. sp.); Triogma (1 Eur., 1 N. Am. sp.) ; Phala- 

 crocera (1 Eur., 1 N. Am. sp.) ; Plychoptera (5 Eur., 3 N. 

 Am. sp.). 



The comparison of the smaller genera again discloses a re- 

 markable agreement in the number of species ; the differences, 

 where they occur, are in most cases in favor of the European 

 fauna, and are probably due, in a great measure (for instance in 

 the genus Anisomera), to the imperfect knowledge of the North 

 American fauna. . 



I have shown the points of agreement between the two faunas. 

 The statement of the differences requires much more caution, as 

 the incomplete knowledge of the North American fauna is here to 

 be especially taken into account. It is almost certain that some 

 of the genera, enumerated above as peculiar to America, will 

 never be found in Europe (for instance Toxorrhina, Elephanto- 

 myia, Eriocera) ; on the other hand, it is far from certain that the 

 genera hitherto found in Europe only, may not yet be discovered 

 on the American continent (as Orimarga and Elliptera). As 

 far as my knowledge goes, the difl'erence between the two faunas 

 may be expressed in the following terms : Whenever the North 

 American fauna diffe7-s from the European in the occurrence 

 of a p)eculiar generic form, or in a marked prevalence of 

 another, this difference is due, either to an admixture of South 

 American forms, or of forms peculiar to the amber fauna. 



If we look over the North American genera, not occurring in 

 Europe, we find that, among those genera, Toxorrhina is a 

 South American and West Indian form ; Elephantomyia occurs 

 in amber ; Eriocerae with short antennse are abundant in South 

 America ; those with long antennae in the male sex have been 

 found in amber. Protop)lasa is represented by Tanyderus in 



