46 
William Morton Wheeler 
antennae to establish an independent genus for its reception, but 
although Monomorium is made np very largely of species witli 12-jointed 
antennae in the worker and female phases, a few of the species 
(M. orientale Mayr and M. atomus Forel) have 11-jointed and one 
(M. decamerum Emery) even has 
10-jointed antennae. As the name 
gracillimum is preoccupied in the 
genns Moüomorium by a species des- 
cribed by F. Smith in 1861, it be- 
comes necessary to give the amber 
species a new name. 
1 9 workers in the Geolog. Inst. 
Koenigsberg Coli, are referable to 
this form, namely: No. 84/3736, No. 
Fig. 15. Monommmm^m^yrinnum nom. nov. , , 0^3702 (Mayr’s type), B 252, 
B 18 665, B 18880, B 14742, XX 
B 301, B 19191, B 19998 (two workers in one block), XXB 607, 
XXB 594, XXB 1054, and six without numbers. One of the num- 
bered specimens is in the same block as a worker of Iridomyrmex 
geinitzi Mayr. There are also five workers in the Klebs Coli, namely 
K 4274, K 4269, K 1031, K 948 and K 2646. 
M. mayrianum is very similar to M. pilipes, but besides having 
11-jointed antennae, it is smaller (1,5 — 1,8 mm), the mesoepinotal con- 
striction is less pronounced, the epinotum is less angular, with a more 
rounded and convex base and the petiolar node seems to be less com- 
pressed antero-posteriorly and of about the same size and shape when 
seen from above as the postpetiole. The sculpture, pilosity and color 
are very much like those of M. pilipes. 
Tribe Solenopsidiini Emery. 
Genus Erebomyrma Wheeler. 
Erebomyrma antiqua (Mayr). 
PheidoJogpion antiquus Mayr, Beitr. Naturk. Preuss. I, 1868, p. 93, Taf. V, Fig. 95, 96, 9. 
Aeromyima antiqua Emery, Mem. Accad. Sei. Bologna (5) I, 1891, p. 577 9l Dalla 
Torre, Cafalog. Hymen. VII, 1893, p. 78; Handlirsch, Foss. Insekt. 
1908, p. 872. 
Aeromyrma sp. Wheeler, Ants, their Structure, Development and Behavior, 1910, 
p. 163, Fig. 92, <y. 
Worker (Fig. 16a and b). Length about 2 mm. 
Closely resembling the worker of E. longi Wheeler in shape. 
Head rather large, subrectangular, somewhat longer than broad. 
