inl 
No. 418.] NESTS OF AMERICAN ANTS. 807 
facilitate symbiosis. The queens, as I have shown in the case 
of L. emersoni, may retain the excavating instinct and the 
instincts which relate to the care of the larva. Wasmann 
(91, p. 219, footnote) saw the queen of L. tuberum var. nigri- 
ceps removing the larvae and pupz when the nest was disturbed, 
and I have recorded above a similar observation on L. canaden- 
sis. More recently I have seen both the winged and deálated 
queens in a nest of Z. Jongispinosus carrying away the larve 
quite as busily as the workers. It is as Forel says (74, p. 3 39): 
“Les 9 vivent presque comme les $; elles sont seulement 
moins aptes au travail." 
6. The similarity in instinct between the queens and workers 
of Leptothorax finds its physical expression in the frequent 
occurrence of intermediate, or ergatogynous, forms. So-called 
microgynic individuals, or winged queens no larger than the 
workers, have been frequently observed by Forel (74, p. 341) 
and Wasmann ('95, p. 618) in L. acervorum. Those observed 
by the latter author also showed color transitions between the 
normal queens and workers. Adlerz (86, p. 77) found micro- 
gynic individuals in Z. acervorum, muscorum, and tuberum. 
Still other ergatogynous forms, which may be called ergatoid 
queens, are represented by the large ocelligerous workers of 
L. emersoni described and figured in the first part of this 
paper (pp. 434, 436). These individuals bear a striking and 
suggestive resemblance to the ergatoid queens of Fi omognathus 
sublevis described and figured by Alderz Wasmann (95 
P. 619) also records the occurrence of what he calls ''erga- 
togyne Mischformen," or individuals completely transitional 
between the queens and workers, in colonies of L.acervorum 
and Formicoxenus nitidulus. 
It is possible to draw still further inferences from the hetero- 
geneous instincts exhibited by the genus Leptothorax and its 
allies. Viewed as a whole, these different symbiotic relations 
` cannot be said to bear the ear-marks of internal developmental 
Causes operating in a perfectly determinate manner. Indeed, 
appearances are quite otherwise and seem rather to pomt 1 
indeterminate variations which have been and are still in 
process of being seized on and fixed by natural selection. 1t 
