The Ants of the Baltic Amber. 
111 
D.janeti and G. chaperi, would, on this supposition represent relicts 
of this evolutionary process, which are today leading a precarious 
existence in the islands of the Malay Archipelago. 
These considerations will explain why I cannot regard the Se- 
paration by Emery of the existing Dimorphomyrmex in a tribe distinct 
from the QjJcophyllini, as satisfactory, for this genus is evidently 
closely related to Gesomyrmex as shown by G. annectens and this 
latter genus is generally recognized as closely related to (Ecophylla . 
The Separation was made by Emery solely on the structure of the 
gizzard, but this single character, though important, can hardly be 
made to outweigh the numerous external resemblances between these 
three genera and the fact that they merge into one another so in- 
tim ately. 
Besides the two amber species described above, a third extinct 
species has been referred by Emery to the genus Gesomyrmex. This 
is G. corniger of the Sicilian amber, which is of upper Miocene age. 
A study of Emery’s figures and description of this form, however, 
fail to convince me that it really belongs to Mayr’s genus, although 
it is evidently an allied form. The shape of the head and thorax, 
which are both armed with long spines, the position and shape of 
the eyes and the dentition of the mandibles are so peculiar that in 
my opinion it should be regarded as the type of a new genus, for 
which I suggest the name Sicelomyrmex. This ant is evidently a 
much more highly specialized and geologically more recent form than 
G. hoernesi and suggests that the group of Camponotince with 8-joint- 
ed antennss in the worker phase may have reached its highest develop- 
ment in the Miocene of Europe before becoming extinct on that 
continent. At the present time this group is represented merely by 
G. chaperi and D.janeti in Borneo and Sumatra and by two species 
of Aphomomyrmex (A. andrei Emery and A. hewiiti Wheeler) in the 
former island. 
Genus Prodimorphomyrmex , gen. nov. 
Worker. Related to Dimorphomyrmex. Head large, flattened, 
longer than broad, broader behind than in front, with straight sides 
and broadly excised posterior border. Eyes large, oval, but not reni- 
form, narrower in front than behind, smaller than in Dimorphomyrmex , 
less than l j 2 as long as the head, placed at the middle of its longi- 
tudinal diameter. Ocelli present, minute. Clypeus small, flat, its 
anterior border entire, broadly rounded, not projecting. Frontal 
carinse distinct, widely separated, straight, diverging behind and ex- 
