The Ants of the Baltic Amber. 9 



not in existence during the early Tertiary. We must assume either 

 that it was then as now confined to the tropics and immediately 

 contiguous subtropical belt or that the eminently terrestrial or even 

 hypogaeic habits of its species excluded it from the amber. The former 

 alternative seems to me to be much the more probable, because I have 

 found specimens of recent Dorylince (Anomma) in the Zanzibar copal. 

 After this brief account of the subfamilies we may proceed to 

 a comparison of the genera of the amber with those of recent ants. 

 Of the 43 genera, 19 or 44,1° q are extinct and 24 or 55,8 % are still 

 extant. The extant and extinct genera in the subfamilies Ponerince, 

 Myrmicince and Dolichoderince are nearly equal in number, but of the 

 CamponotiiKB only 4 are extinct, while 9 have survived to the present 

 time. This proportion of extinct to recent genera is not widely diffe- 

 rent from that found by Ulmer in his admirable study of a very 

 different group of insects, the Trichoptera^), which are represented in 

 the amber by 30 (53,5 °/o) extant and 26 (46,4 %) extinct genera. In 

 the following list the names of the Formicid genera are followed by 

 the number of known amber species in parentheses, and the extant 

 genera are grouped according to the distribution of their recent species, 

 the extinct genera with indications of their nearest affinities. 



A. Extant Genera. 



1. Cosmopolitan: 



Ponera (2) Prenolepis (2) 



Aphcenog aster (3) Camponotus (1) 



2. Tropicopolitan: 



Platythyrea (1) Iridomynnex (5) 



Euponera (Trachymesopus) (1) Dolichoderus (Hypoclinea) (9) 



3. Paleotropical: 



Sima (5) Plagiolepis (6) 



Monomorium (2) (Ecophylla (2) 



4. Indomalayan and Australian: 



Ectatomma (Rhytidoponera) (1) Dimorphomyrmex (2) 

 Vollenhovia (2) Pseudolasms (1) 



Gesomyrmex (2) 



5. Circumpolar: 



Stetiamtna (1) Liometopum (1) 



Myrmica (1) Lasius (5) 



Leptothorax (5) Formica (6) 



^) Die Trichopteren des baltischen Bernsteins. Beitriige zur Naturkunde Preuflenf^, 

 herausgegeb. v. d. physik.-ukonom. Gesell. Konigsberg. X, B. G. Teubner, Le'pzig und 

 Berlin, 1912, 380 pp., 480 text-fige. 



