554 Wisconsin Academy of Sciences^ Arts^ and Letters. 
then inverted over a hollow slide at the same time being sealed 
with vaseline. Such preparations preserve the natural form of 
the plasmodia and are free from the movements which result 
from using an oil immersion objective on an ordinary fresh prep¬ 
aration. For the study of the preparations an apochromatic im¬ 
mersion objective was used; it being found impossible to deter¬ 
mine the colors of the small granules of the plasmodia with an 
acromatic objective. The greater part of our work has been done 
on fresh preparations, as the study of these is believed to give 
the most reliable characters for systematic determinations. All 
measurements given were made on fresh preparations, the out¬ 
lines being drawn with the camera lucida and measured with a 
stage micrometer. 
3 . Diagnosis of Species. 
a. Heniieguya wisconsinensis. Manor and Strasser. 
This species has been discussed by us in a previous paper 
(1916) and was there recorded from the yellow perch, Perea 
flavescens Mitchill. We now record its occurrence in the sun- 
fish, Lepoinis pallidus, Mitchill, the large mouthed black bass, 
Micropterus salmoides Lacepede, and the speckled trout, Sal- 
velinus fontinalis, Mitchill. As there are considerable differences 
in the parasites found in these four fish, we are doubtful whether 
they ought not to be assigned to different species, but content 
ourselves with recording the differences we have found. 
We quote our original description of Henneguya wisconsin¬ 
ensis: —^‘The Myxosporidium (plasmodium) is usually elongated 
and has the general form of a Umax amoeba, and may reach a 
size of 300 x 70/i, Ectoplasm and endoplasm are clearly to be dis¬ 
tinguished. The pseudopodia are lobose. ” To this we have to 
add the following: In Lepomis pallidus the pseudopdia may 
be very thin and many times as long as the body of the plas¬ 
modium. In Micropterus salmoides fine radiating! pseudopodia 
are found extending from all parts of the body giving some of 
of the plasmodia the general appearance of a heliozoan, while 
in others the pseudopodia are short, fine and bunched together, 
giving the part of the plasmodium from which they arise a vil- 
late appearance. The latter pseudopodia undoubtedly function 
in attaching the plasmodium to the wall of the bladder. In 
Salvelinus fontinalis the plasmodium shows only lobose pseudo- 
