1897-98. ] The Upper Elf Loch, Bratds. 379 
In some of the Daphniade, and perhaps also in some of the 
other groups, broods of these pseudova are produced at more 
or less frequent intervals, and sometimes in considerable 
numbers during the life of the female; but in most of the 
Lynceide the production of summer eggs does not appear to 
be so frequent or so numerous. The winter- or resting-eggs 
—the latter name, as will be apparent from what follows, is 
the more appropriate one—are said to be true fertilised eggs, 
and they are produced usually towards the close of the life 
of the female, their production being her last efforts for the 
propagation of the species. In the Daphniadz, and probably 
also in the Lynceide,—certainly in some of them,—these 
resting-eggs are enclosed in a portion of the test of the 
mother that is somewhat modified for the purpose, and is 
technically called the ephippium (Gr. ephippion, a saddle, from 
its shape). Speaking generally, two resting-eggs are produced 
in the Daphniade, but only one in the Lynceide. These 
eggs appear as dark-coloured, or almost black, oval bodies, 
within the ephippium. The production of the ephippia is not 
limited to autumn or winter, as they may be produced at any 
season, just as the so-called summer eggs may be observed at 
all seasons—in winter as well as in summer. Resting-eggs, 
after being set free, and whether enclosed in a true ephippium 
or not, may, and frequently do, lie dormant for a considerable 
period, hence the name “ resting-eggs.” It is doubtful if the 
causes that in due time excite the active development of these 
resting-eges are yet clearly understood: increase of temperature 
may have something to do with it. Ephippia enclosing one or 
two eggs are often met with by the pond-worker, and occa- 
sionally prove a source of perplexity: it is therefore hoped 
that what has just been stated as to their true character may 
prove useful to some. 
Another interesting feature in the history of the Cladocera 
is the entire absence, or extreme rarity except at irregular 
and more or less distant intervals of time, of the males of 
many of the species. The Daphniade may be referred to 
as furnishing examples of this phenomenon. The female 
Daphnia is frequently very prolific. She may develop brood 
after brood of young at short intervals for a considerable 
time, and these young, in their turn, may give birth to other 
