200 
Psyche 
[December 
studied in Professor Wheeler’s laboratory at the Bussey Institu- 
tion, represents a new case of mermithization, similar to that of 
Pachycondyla fuscoatra, described by Emery. 
Pachycondyla striata was found in small colonies under dead 
leaves. It stings severely and when disturbed can bury itself 
quickly into the ground. I encountered the parasitized specimen 
of Pachycondyla striata running along a trail in the forest in the 
neighborhood of Puerto Bertoni, where the famous naturalist 
Dr. M. S. Bertoni lived. The movements of the ant were slow. 
The differences presented by the morphology of the pa- 
rasitized Pachycondyla striata in comparison with an unparasitized 
specimen may be seen from the accompanying figures. 2 The 
gaster of the itiermithergate is very voluminous and swollen. In 
the normal ant the abdominal segments are fitted into one 
another so as to allow the abdomen to dilate as a whole. But in 
the parasitized individual some of the segments are more or less 
separated from one another, so that the abdomen is increased in 
length from 6 . 5 mm. in a normal to 8. 5 mm. in the mermithergate 
individual and from 2.25 to 3 mm. in diameter. The petiole of 
the parasitized ant is narrower and lower, than in normal workers. 
Some modifications in the thorax were also observed. The 
pronotum of the mermithergate is shorter and the epinotum 
narrower than in normal P. striata. 
The greatest difference is discernible in the head, which in 
the parasitized specimen is conspicuously smaller and less robust, 
i. e. narrower and shorter, and of a peculiar narrow, more rec- 
tangular shape behind the eyes. There are no traces of ocelli. 
The mandibles of the infected specimen are narrower and 
smaller, the antennal scapes decidedly shorter and a little thinner. 
The funiculus is also slightly shorter. 
The surface of the body is smoother and more shining than 
in normal P. striata workers, owing to the fewer hairs on all 
parts of the body. The color of the hairs is also different. In 
the parasitized specimen they are more grayish, but in normal 
P. striata they are golden-yellow. 
In the intersexual form of P. striata we have parasitic cas- 
tration and mingling of the normal secondary sexual characters. 
2 Made by camera lucida. 
