On the Diptera of the Amber-fauna. 307 
now known certainly to occur in amber, are the following sev- 
enteen: Xylophagide, Tabanide, Leptide, Cyrtide, Asilida, The- 
reuidee, Bombylide, Syrphide, Pipunculide, Hybotide, Empide, 
Tachydromide, Dolichopodide, Helomyzide, Micropexide, Diop- 
side and Phoride. The families whose existence in amber is tol- 
erably well established, are the following ten: Myopide, Tachi 
nide, Deride, Muscide, Anthomyide, Sciomyzide, Sapromyzxda, 
Ephydrinide, Drosophilide and Oscinide. As families, which 
seem not to be represented in amber, we may name six: the 
Sarcophagide, Lonchwide, Heteroneuride, Opomyzide, Piophilide, 
and Geomyzide. Finally, there are eighteen families of which 
it is perfectly certain that not a single species has been found in 
amber, namely: Stratiomyide, Acanthomeride, Mydaside, Hir- 
moneuride, Scenopinide, Platypezide, Lonchopteride, Cistride, 
Cordyluride, Psilide, Ortalide, Trypetide, Phycodromide, Sep- 
Borboride. Of th 
= 
. e 
families above named, the Dolichopodide far exceed all the others 
A seemiage The proof of its correctness by the soeaieaton 
f the species, enclosed in amber derived from different locali- 
~_ If the speci is found enclosed in the same piece with the spe- 
cies b, iin dhae-beca eau to occur in another piece ed 
with c, we may presume that they belong to the same district- 
fauna. I have therefore devoted especial attention to those pieces 
of amber which contained several species, and have endeavored, 
