122 
William Morton Wheeler 
and coloration. The color Variation, whicli ranges from black through 
brown and red to yellow, is probably largely dne to preservation, but it 
is not impossible that several color varieties were already in existence 
in the Lower Oligocene. 
That the species of Lasius of this age were already supporting 
myrmecophilous mites is shown by two workers in the Geolog. Inst. 
Koenigsberg Coli. (B 5345 and B 5187), each of which bears a large 
Gamasid attached to the ventral side of the base of the left hind tibiae. 
The close similarity in the position of the two specimens suggests that 
these mites had already acquired the habit so remarkably developed 
in some of the recent species of Antennophorus and Cillibano , of 
attaching themselves to very definite regions of their host’s body. 
Lasius pumilus Mayr. 
Lasius pumilus Mayr, Beitr. Naturk. Preuss. J, 1868, p. 46, Taf. II, Fig. 33 Dalla 
Torre, Catalog. Hymen. VII, 1893, p. 190; Ern. Andre, Bull. Soc. 
Zool. France, XX, 1895, p. 82; Handlirsch, Foss. Insekt. 1908, p. 860. 
Only the worker of this species was described by Mayr, and 
notwithstanding much search I have been unable to find the male and 
female in the material under Observation. The worker is extremely 
small for a Lasius, measuring, according to Mayr, only 1,5 mm. Some 
of the specimens I have seen are even smaller (1,25 mm). The terminal 
joints of the maxillary palpi are long and subequal as in L . schieffer- 
deckeri and the recent niger and show no tendency to decrease in 
length distally as in the flavus and umbratus forms. The species can 
be readily distinguished from schiefferdeckeri not only by its size but 
by the pilosity and the much shorter antennal joints. Joints 2 — 4 of 
the funiculi are distinctly broader than long and the remaining joints, 
except the last, are scarcely longer than broad. The erect hairs are 
absent on the head, thorax and appendages and are present only on 
the gaster, and especially at its posterior end where they are long, 
sparse and delicate. The epinotum is shorter than in schiefferdeckeri 
and the petiole is rather high and obovate when seen from behind, 
with a rather sharp and, in some specimens, feebly emarginate superior 
border. The various specimens show the same ränge of actual color 
variations as schiefferdeckeri. 
Mayr based L. pumilus on three specimens, one of which (7511/225) 
is still in the Geolog. Inst. Koenigsberg Coli. I have seen also 67 other 
specimens which I refer to this species, 58 in the Geolog. Inst. Koenigs- 
berg Coli. (B 18 891, XXB 754, B 18157, XXB568, XXB 758, B 18 941, 
XXB 724, B 5447, B 19 708, B 603, B 18 905, XXB 512, B 18 784, 
