344 Dr. Franz Léw on a new 
was also observed by Dr. Kiihn in the case of Anguillula 
dipsact. 
I have hitherto met with the deformations produced by 
the Anguillulide under consideration on the leaves of Achil- 
lea millefolium, only in some parts of the Pfalzauthal in 
the Wienerwald, and always only in very small numbers. 
Whether the whole plant is mjured by it I could not ascertain, 
as I have always found it only upon the leaves of isolated 
plants of scanty growth standing upon poor soil, never upon 
strong and luxuriant plants. 
The Anguillule themselves agree exactly im their principal 
characters with the other known forms infesting plants. ‘The 
only specific differences are derived from the size and colour 
of the body, and the proportions of its parts to one another. 
But before indicating the specific characters of the milfoil- 
Anguillula, I will give an accurate description of it. 
The Anguillule of the milfoil have an elongated body, 
attenuated towards the two ends, round in transverse section, 
and of undecided colour. They may be said to be translucent 
whitish with a greenish yellow shimmer. ‘This shimmer, how- 
ever, appears to proceed from their food, which in all proba- 
bility consists of the above-mentioned greenish yellow fluid 
contained in the galls. By transmitted light the body is seen 
to be entirely filled with granules of different sizes and forms, 
which prevent any examination of internal organization. ‘The 
external integument of the body is rather thick, quite smooth, 
and shining. In the middle of the anterior, obtusely rounded 
end of the body is the mouth, which is continued within into 
the cesophagus, which runs straight for a very short distance, 
and at a distance from the mouth equal to the transverse 
diameter of the body at the same spot presents a globular 
muscular dilatation. From this it runs backward in an in- 
distinctly visible tortuous line, and at the second curvature 
loses itself entirely in the granular contents of the body. In 
Anguillula dipsact Dr. Kiihn observed that the portion of the 
cesophagus situated behind the globular dilatation was also 
somewhat tortuous, and presented at its extremity a second 
similar dilatation, which [ could not detect in the Anguillula 
of the milfoil. The other Anguillulide (e.g. A. fluviatilis, 
acett, glutinis, mucronata, linea, &c.) possess similar rounded 
muscular dilatations of the cesophagus*. 
The posterior extremity of the body is rather rapidly atten- 
uated, and terminates in a much finer point than the anterior 
end. Prof. Grube has already indicated that all Anguillulee 
* Grube, “Ueber einige Anguillulen, und die Entwicklung von Gordius 
aguaticus,’ in Arch. fiir Nature. Jahre. xv. (1849), p. 358. 
q g 8 »?P 
