The Ants of the Baltic Amber. 
91 
males in the Geolog. Inst. Koenigsberg Coli. (XXB 626, XXB 52, 
XXB 112, XXB 117, B 18750, XXB 1118, B 18645, XXB 7118, 
XXB 137, B 18934, B 18812, B 27286, B 19441, XXB 1110, XXB 
1114, B 19744, XXB 761, XXB 1531, B 18367, B 1845 etc), 650 
workers, 2 males and 2 females in the Klebs Coli. (K 1749, K 4244, 
K 4287, K 2631, K 1757, K 859, K 1734, K 5784, K 941, K 3699, 
K 1441, K 3545, K 1745, K 2624, K 2660, K 4492, K 1027, K 4058, 
K 4468 etc.), 4 workers in the Brussels Museum, 46 workers and one 
male in the Berlin Museum (240, 243, 247, 251, 257, 258, 294, 308, 
314 etc.) and 73 workers and one male in the Haren Coli. (67, 104, 
134, 291, 337, 859, 488, 980, 983, 1841 etc.). In addition to these 
4539 specimens I have examined 174 of the 268 specimens recorded 
by Mayr as belonging to the Physical Economic Society Collection (to 
day the Geolog. Inst. Koenigsberg Coli.), including the types of the 
worker and female. The male type, which I have not seen, was in 
the Menge Coli. 
The occurrence of 2 — 4 specimens of I. goepperti in single pieces 
of amber is not uncommon, and occasionally the number of indivi- 
duals thus enclosed is much greater. Thus in the Klebs Coli, there 
are the following inclusions: K 108 with 9 workers, K 4168 with 12, 
K 886 with 15, K 828 with 15 and K 839 with 20 workers. And in 
the Geolog. Inst. Koenigsberg Coli, three blocks without numbers 
contain 27, 28 and 50 workers respectively. The great abundance of this 
ant is also attested by the fact that it often occurs in the same block 
with other species, especially with Lasius schiefferdeckeri and 1 . geinitzi. 
In the Geolog. Inst. Koenigsberg Coli, there is one block of 
amber (without a number) containing a worker I. goepperti with its 
larvae and another block in the same Collection (also without a n amber) 
encloses 13 workers mingled with a number of Aphids! 
These various specimens seem to me to show conclusively that 
I. goepperti was everywhere abundant in the amber forests, that it 
formed populous colonies, whose workers foraged in files and attended 
plant-lice on the oak and Pinites trees, much as the species of Lio- 
metopum of the present day forage on the conifers and oaks in the 
Western United States, and on the oaks in Austria, Italy and the 
Balkan Peninsula. 
lridomyrmex samlandicus, sp. nov. 
Worker. (Figs. 43 u. 44.) Length 5,5 — 6 mm. 
Head, excluding the mandibles, about as long as broad, convex 
above, broadest in the middle, narrower in front than behind, with 
