246 MOXOGRAPn or the laboulbeniace^. 
hosts inhabiting the margins of running water were much more likely to be parasi- 
tized than those fonnd along the borders of ponds or of still water generally; but this 
has certainly not been my own experience, and the margins of ponds or of boggy 
i 
places generally have always proved as rich in LaboulbeniaceiB as those of brooks or 
rivers. It is also worthy of note that the statement made by the same author that 
iridescent hosts are not infected has not proved to be true in my experience. 
The relation of the parasite to its host as regards its nutrition has already been 
referred to, and there can be no doubt that the fluids of the insect are absorbed by 
osmosis through the membrane of the foot or haustorium, whether this be a highly 
developed penetrating organ, as in Rhizomyces or Moschomyces, or consists merely in 
a sucker-like external attachment. 
w 
The relation of the parasite to its host, in position, is a matter of interest for sev- 
eral reasons ; for, although all parts of the latter may be infested, the antenna3, the 
eyes, the mouth parts, the anal plates, — in fact any portion exposed when the insect is 
at rest, — certain species exhibit a very reniarkable defmiteness in regard to their point 
of attachment. In some forms, like Lahoulkmia Nehriw, or L. Gakrltm. the i^arasite 
idiscriminately all over tl 
uly at the tips of the elv 
L. tennmalis, L. fumosa, or Z. lux- 
it region about the extremity of 
abdomen. Others, like L. panmki and L. arcaata, have been found only on the 
1 in a definite position. L. IlarpaU, again, occurs on one 
species alway 
side only, along the anterior inferior margin of the thorax and the adjacent margin of 
the prothorax. L. contorta, L. umhonatfi, L. elcgans, L. lepida and L. tcmna all occur, with 
very rare exceptions, on the prothorax just below the external margin, usually on a 
d 
mity of the 
may be noted in passing that, especially as regards the 
tioned species have a familv resembl 
ex- 
Instances like those just enumerated might be multiplied ; but by far the most remark- 
able examples occur in the genus Chitonomyces.' Species of this £renus growing, for 
by 
pie, on LaccopJulm maculosus, can be distinguished, as a rule, with certainty merely 
loting their relative positions. C. parodoxus is invariably fixed to the margin of 
left elytron about half-way between its base and apex ; C. marni 
3 
within the margin of the same elytron nearer the apex. C, Uchanopliorus is found 
only on one of the inferior median anal plates (always the same plate), and 
so on 
ed of any d 
pecies that infest 
only instance which I 
ely found attached to the left posterior le 
Why such constancy in position should 
position being in the case of G. margi 
O 
some cases, and 
