On the Diptera of the Amber-fauna. 313 
made me acquainted with three other intermediate forms of this 
kind, two from the United States and one from Cuba. These 
species also belong to the relationship of Hlectra, Chrysothemis 
and Rachicerus, although they cannot be referred to either of 
servations on the Dipterous fauna of the Amber,” published in 
1 A part only of these genera owe their existence to the 
necessity of establishing for these fossil species generic distine- 
tions based upon slighter plastic characters than those usually 
admitted for the separation of living species, and have therefore 
less claim to be taken into consideration here. Another portion 
consists for the most part of very striking species, easily distin- 
ished from all the known living genera. But this circumstance 
re- 
and for which I me 
, the name of Arthropeas, on account of its peculiar su 
uliform antenna. After having found Arthropeas nana om — 
ber, I received a closely allied species from Eastern 5! ra, 
A, Sibirica m., and now I possess in A. Americana m., a 
from the United States which is even somewhat more nearly re 
a A. nana. 
‘he genus Bolbomyia, two whic 
Was remarkable for “the difficulty of assigning a suitable 
tion for it in the system, as ee 
necies of which occur in — 
