378 The Upper Elf Loch, Braids. [Sess. 
is rather a distinct and readily recognised form, and was not 
at all rare in the September gathering referred to ; yet, strange 
to say, the only time it has with certainty been noticed since 
was in the last gathering of the series, collected on the 23rd 
April last, when only one or two specimens were obtained. 
It may be stated in passing that Canthocamptus inornatus 
has also been recently, and for the first time, observed in 
Duddingston Loch. 
These, then, are a few of the facts bearing on the distri- © 
bution of the Entomostraca which our examination of this 
miniature loch has brought to light. They indicate how 
much interesting information a regular and systematic re- 
search, even of a very limited area, may yield. The curious,. 
and apparently erratic, appearance and disappearance of the 
species we have specially referred to explains also to some 
extent why one collector may be more successful than another, 
or why the same collector may obtain a richer gathering at 
one time than at another. | : 
As the study of the Entomostraca is now receiving greater 
attention, and many microscopists and pond-workers are doubt- 
less desirous of becoming more familiar with them, the follow- 
ing notes on their reproduction may be of some little value 
to such amongst our own members. The reproduction and life- 
history of the Entomostraca have long engaged the attention 
of naturalists, and are still subjects of considerable interest to 
students of these crustaceans. The Cladocera, one of the 
more important orders of the Entomostraca, is of special in- 
terest, because of the peculiar reproductive processes observed: 
in several of the groups composing the order. Most part of 
the Cladocera are fresh-water organisms: a few of the genera, 
however, are marine, and species belonging to these marine 
genera are sometimes observed in immense numbers, so that 
the lack of variety in marine forms, as compared with those 
inhabiting the fresh waters, is somewhat compensated for by 
the greater number of individuals that are occasionally met 
with. | 
All, or nearly all, the fresh-water Cladocera produce two 
kinds of “eggs ”—viz., summer eggs, and winter- or resting- 
eggs. The summer eggs are considered to be, not true eggs, 
but “buds,” and they have received the name of “ pseudova.” 
