A NEW FIELD FOR THE MICROSCOPIST. 
115 
powerful and high-class magnifying powers referred to in our 
opening sentence. 
It will no doubt be remembered by many readers of this 
Journal that certain members of the Flagellate Protozoa, em- 
bracing several of those free-swimming monads which occur 
abundantly in fish- and other animal-macerations, have already 
been brought before their notice.* On this occasion, however, 
it is proposed to give a brief descriptive outline, with illustra- 
tions, of an extensive series of forms that have so far, on ac- 
count of their exceedingly minute size, altogether evaded the 
notice of the microscopists of this country, but which at the 
same time most certainly surpass all previously discovered types 
equally in the wonderful symmetry of their individual form and 
in that of their aggregated mode of growth. So long ago as the 
year 1866 a few stray members of this Flagellate group, to which 
attention will now be directed, were made known to the American 
scientific world by Professor H. James Clark, of Pennsylvania, 
U.S.A., who described and figured four species only, three of 
these inhabiting fresh-, and the remaining one salt-water. Most 
unfortunately for science this authority did not long survive his 
discovery of these new forms, and had, consequently, no oppor- 
tunity of further extending and fully maturing his acquaintance 
with the same. Since the death of Professor Clark no other 
investigator, with the exception of the contributor of this article, 
appears to have knowingly encountered a single representative of 
the group in question, which may thus be said to have vanished 
from scientific cognizance. 
The first acquaintance made by the writer with the new 
group of Flagellate Monads now to be introduced was in the 
autumn of the year 1871, when occupied in investigating the 
infusorial fauna of a small pond situated in the North London 
district, and fed by water from the New Eiver Company. What 
at first sight during these researches presented the aspect of 
numerous closely aggregated colonies of a minute species of 
Epistylis , resembling the E. botrytis of Ehrenberg, proved upon 
more accurate examination and with the aid of a magnification of 
about 700 diameters, to be identical with the new type introduced 
by Professor Clark a few years previously, under the title of Codo- 
siga pulcherrima. A representation of this earliest discovered 
and very elegant compound pedicellate monad will be found at 
Plate III. fig. 9, accompanying this article. The identity and 
structural peculiarity of this type having been once recognized, a 
very brief investigation sufficed to detect in the water of this same 
pond the whole of the three fresh- water species originally found 
* See article on “ Recent Researches in Minute Life,” by H. J. Slack, 
F.G.S., Pop. Sc. Rev., vol. xiv. p. 245. 1875. 
