REVIEWS. 59 



has enumerated, as it appears, 2,335 species of British Diptera, exclusive 

 of the Pulicidce, which neither he nor Zetterstedt has included in this 

 order. Of these, 650 belong to the families treated in detail in the 

 first of Walker's volumes, where they are reduced to 620, out of which 

 470, or more than three-fourths, are 'described in the DIPTERA SCAN- 

 DINAVLE. If the same proportion hold good in the remaining families, 

 the total number of British species known would be about 2,130, 

 and we might expect above 1,600 of them in Zetterstedt. Walker, 

 however, thinks the Tachinides and Anthomyzides are much more 

 numerous than has been supposed hitherto. Adopting his estimate of 

 them (uncertain as such a computation of species unnamed may be), we 

 should have nearly 400 to be added to the number of these given in the 

 Guide, still leaving the total of British Diptera. short of the Swedish by 

 about 950 species. Nor does this seem a very improbable excess on the 

 other side, taking into account the extent of the peninsula, with the 

 greater variety of temperature and elevation, the tracts that border on the 

 Arctic circle, the Alpine chains of Lapland and Norway, the breadth of 

 primeval forest, and the more genial summer of the south of Sweden, 

 parted only by a narrow strait from Jutland and the vicinity of central 

 Europe. Accordingly, the Swedish fauna has representatives of many 

 Continental genera unknown with us Ceroplatus 6 spp., Gnoriste 3, 

 Penthetria, Macropeza, Chionea 2, Pachystomus, Canomyia, Hexatoma, 

 Microsania 2, Gloma, Pelecocera 2, Stachynia, Lophosia, Wahlbergia, 

 Cystogaster, Rhinophora 2, Dialyta, Selachops, Colobaaa ; against which we 

 can set off only Mochlonyx, Sycorax, Geranomyia, Actina, Spania, Euthy- 

 neura 2, Ulidia, Lucina, Eurhina, Camarota, Tichomyza, Nycteribia 2. So 

 far as known at present, the following Pachyneura, Corynocera, Psilocon- 

 opa, Sph&rogaster, Anthalia, Iteaphila, Hormopeza, Nephrocerus, Gymno- 

 peza, Ciuochira, Ectinocera, Psasroptera, Rhynchasa, Amphipogon, Earomyia, 

 Lobioptera, Leptopteryx appear to be peculiar to the Scandinavian fauna; 

 while the British islands claim on their side Leptomorphus, Epidapus, 

 Cluuio, Ragas, Aphrosylus, Tethina, Atissa, Glenanthe, Canace, unknown 

 to Sweden. In certain genera of wide geographical range, and rich in 

 species, the great disparity between the lists is probably owing, in part, to 

 the neglect of them by the British collectors. The genus Rhamphomyia 

 numbers only 24 species in Curtis's Guide, reduced to 10 by Walker ; 

 while Zetterstedt has described no less than 72, and, out of that number, 

 21 as new species of Swedish authors. Other genera augmented largely, 

 in like manner, if not in equal proportion, are Anthomyia with new species 

 122 to 68 previously described, Alicia 176 to 66, Tachina 112 to 94, 



