128 Transactions of the Royal Microscopical Society. 
The ordinary workers have in Polyergus rufescens about 400, in 
Lasius fuliginosus 200, in Tapinoma erraticum, 100; in Plagio- 
lepis pygmeea, 70 to 80; in Lasius flavus, about 80; in Bothrio- 
myrmex meridionalis, 55; in Strongylognathus testaceus, Stenamma 
Westwoodii, and Tetramorium ceespitum, 45 ; in Pheidole pallidula, 
about 30 ; Myrmecina Latreillei, 15 ; Solenopsis fugax, 6 to 9 ; 
while in Ponera contrada there are only from 1 to 5, and in 
Typhlopone the eyes are altogether wanting. 
The number of facets seems to increase rather with the size 
of the species than with the power of vision. The whole subject is 
one of great interest and difficulty. 
The ocelli are never more than three in number, disposed in a 
triangle with the apex in front. Sometimes the anterior ocellus 
alone is present. In some species the workers are altogether with- 
out ocelli, which, however, are always present in the queens and in 
the males. 
The mouth parts are the labrum, or upper lip ; the first pair of 
jaws or mandibles ; the second pair of jaws or maxillae, which are 
provided with a pair of palpi ; and the lower lip, or labium, also 
bearing a pair of palpi. 
The thorax is generally considered to consist, as in other insects, 
of three divisions — the prothorax, mesothorax, and metathorax ; 
there are, however, grounds into which I will not at this moment 
enter, for considering that the first abdominal segment has in this 
group coalesced with the thorax. Each segment of the thorax 
bears a pair of legs, consisting of the coxa, trochanter, femur, 
tibia, and tarsus, the latter consisting of five segments and termi- 
nating in a pair of strong claws. 
In the males and females the meso- and meta-tliorax each bear 
a pair of wings, which, however, are stripped off by the insects 
themselves soon after the marriage flight. 
The workers never possess wings, nor do they show even a 
rudimentary representative of these organs. Dr. Dewitz, however, 
has shown that the full-grown larv;e of the workers possess well- 
developed “ imaginal disks,” like those which, in the males and 
females, develope into the wings. These disks, during the pupal 
life, gradually become atrophied, until in the perfect insect they 
bear no trace excepting two strongly chitinized points lying under 
the large middle thoracic stigmas. No one not acquainted with the 
original history of these points would ever suspect them to be 
the rudimentary remnants of ancestral wings.* 
Each of the thoracic segments bears a pair of spiracles. 
The abdomen consists of six segments, in the queens and workers, 
that is to say in the females, and seven in the males. The first 
segment, as a general rule, in the Eormickke forms a sort of 
* ‘Zeit. f. Wiss. Zool.,’ vol. xxviii. p. 555. 
