8 THE ESSEX NATURALIST.
in the distance apart of the vertical lines of the network and
an alteration of the spaces between the horizontal lines from
being all equal to a series in ascending ratio from bottom to
top, a modified outline of D. pulex is obtained which is strikingly
close to that of D. hyalina. The third figure (upper to right)
Fig. 1.
is still more interesting for it shows that, if the figure of D. pulex
be transformed in correspondence with a network consisting
of lines spreading out from top to bottom, the horizontal lines
remaining equally spaced, we no longer get an outline of any
known species of Daphnia, but something closely approaching
the characteristic form of the allied genus Simocephalus. In the