306 On the Diptera of the Amber-fauna. 
tion of this supply is the entire Behrendt collection of Diptera in 
amber, to which that of A} ; also rich contri- 
butions from the collection of H. Menge, of Danzig, from that of 
the Physico-economical Society of Koenigsberg, as well as from 
the Thomas collection in the Royal Mineralogical Museum at 
Berlin, without special mention of valuable contributions from 
individual collectors, who have with praiseworthy liberality 
sought to advance the aims of science. 
The investigation of this rich supply of material has, up to 
this time, made known about 850 species of Diptera in amber, 
and these all belong to the division of the Diptera proboseidea, 
while, so far, not a single species of the Diptera eproboscidea has 
been found to occur. Of these 850 species, however, there are 
only 656 in so complete a state of preservation that their specifie 
characters can be Rtabiiinct with absolute certainty. These 
are distributed over 101 genera, of which 50, with 3895 species, 
belong to the Diptera nemocera, and 51, with 261 species, to the 
Diptera brachycera. : 
In the case of the latter, the chemical decomposition of theit 
numbers; the family of the Culicide is the poorest. : 3 
From what has been said above, as to the frog eniee eS ak : 
é ily be w 
place in the systematic arrangement can be assigned only ri 
Sa difficulty. This is true especially for those fons sae ist 
Tutely necessary to distinguish those fainilies of the Diptera — 
brachycera whose occurrence in amber is beyond a dou pie - 
those which are more or less doubtful. The families which» i 
