Black Sea. Heer gave a more southern boundary to the 
amber forests, inferring their occurrence in the area of 
present northern Germany. He was convinced that the 
resin had been carried in mountain torrents to the low- 
lands and shores of the sea. This view of the topography 
of the amber country received confirmation from the 
work of Ulmer (1915) on caddisflies. He concluded that 
fully 35 genera with 73 species from the amber passed 
their larval stages in torrents, that 14 genera with seven 
species lived in quiet water and that seven genera with 
seven species were probably indifferent to their aquatic 
habitat. 
Brues (1988, 1947) concluded from Ulmer’s studies, 
as well as from his own work on amber Hymenoptera, 
that the amber forest type was close to that occurring in 
the mountains of New England today. He thought that 
the presence of pines, spruces, oaks, beeches, chestnuts, 
etc., as well as a similarity of amber insects with modern 
insects collected on tanglefoot fly paper at Petersham, 
Massachusetts, indicated that ‘‘the ecological conditions 
are rather closely reproduced in the hilly forested areas 
of New England at the present time. . .. the flora and 
the fauna were quite similar to those now existing in that 
region.”’ Thus, in his conception that the forest was 
similar to our present boreal ones, Brues did not pro- 
vide an explanation for the tropical elements. 
W heeler (1915) was impressed with the predominance 
of the boreal (Palearctic) affinities of the ants, although 
there were numerous specimens of ants with Indian, 
Malayan and Australian affinities. Rather than explain 
the mixed tropical and boreal assemblages by altitudinal 
or latitudinal variation, he believed that the tropical and 
boreal ants probably did not occur simultaneously. If 
the boreal types were being washed in from the uplands, 
he thought they would not be more numerous than the 
[ 252 | 
