1930] Ttvo Mermither gates of Ectatomma 53 
(queen) characters. Even the enlargement of the abdomen 
is quite unlike that of the normal Ectatomma female, since 
in this caste the gaster is shaped like that of the worker, 
though more voluminous, especially in the region of the 
postpetiole and first gastric segment. The mermithergates 
are interesting for two reasons, first, because they so 
clearly illustrate the compensatory decrease in the size of 
the head and, in Darlington’s specimen, also of the thorax 
as a result of the hypertrophy of the abdomen, which har- 
bors the Mermis, and second, on account of their close re- 
semblance in coloration, abdominal sculpture, and, I may 
add, also in the shape of the posterior portion of the head, 
to another species of the same genus, E. quadridens. This 
singular resemblance may, I believe, be most readily ex- 
plained on the supposition that the specific characters of 
quadridens are probably more nearly those of the ancestral 
species of Ectatomma and that in the mermithized speci- 
mens these characters have been activated as a result of 
metabolic disturbances set up during metamorphosis by the 
parasite. To have produced such a pronounced effect on the 
characters of the adult ant, the young nematode must have 
entered its body cavity during the larval stage. Recently 
Vandel (1927) has maintained that in Pheidole pallidula 
infection of the prepupa by the Mermis is sufficient to pro- 
duce a mermithergate, but his evidence for this contention 
is very meager. I have called attention to the fact (1928) 
that the larvse of the Ponerinse and Formicise (Lasius) spin 
cocoons before the prepupal stage and that it is therefore 
very improbable that the young nematode would wait to 
bore through a tough envelope when it could so easily and 
directly enter the unprotected, thin-skinned larva. That 
this is actually what happens, has been shown by Dr. N. A. 
Cobb, our well-known authority on the nematodes, who 
writes me that he has found the larva of Allomermis myr- 
mecophila Bayliss — ‘fin the body cavity of a queen grub of 
the dark-colored Lasius from Falmouth, Lasius niger 
neoniger .” Falmouth, Massachusetts, is the locality in 
which Dr. A. H. Sturtevant found the many mermithized 
queens (mermithogynes) of Lasius described in my paper 
of 1928. 
