22 ANNALS OF SCOTTISH NATURAL HISTORY 
_ Three visits were made to this part of the Ythan during 
the past summer, twice in July and once in August, and the 
results, briefly set forth in the sequel, were fairly satis- 
factory. 
The bridge which spans the river at the village of Ellon 
is said to be the limit to which the influence of the tide 
extends, but it is not till one gets below Waterton that any 
difference in the Entomostracan fauna of the river begins to 
be observed. It may be stated further that the river for 
some distance both to the east and the west of the bridge 
does not present conditions very favourable to Entomostracan 
life; it is only when we get beyond the railway viaduct on 
the one hand and below Waterton on the other that good 
hunting ground is met with. A little above the viaduct the 
land bordering the Ythan on the south side assumes the 
form of a flat, low-lying meadow, and here, there is what 
looks like part of an old bed of the river, and through which 
the water may still find a channel when in flood. I visited 
this place on 13th July, and at that time this old channel 
had practically no connection with the river except at its 
lower end, and the water it contained, being undisturbed, 
seemed to be a very suitable habitat, and,along with a few other 
places in the neighbourhood, yielded no fewer than forty-two 
species of these minute crustaceans. It was noticeable, how- 
ever, that though there was great variety, the individuals of 
each kind were comparatively few ; it was in marked contrast 
to what is sometimes observed in lochs and ponds, where ~ 
myriads of individuals will sometimes be met with, but with 
very little variety as regards species. Several of the species 
obtained have not before been recorded for the county. The 
part of the river examined in August was the north shore, 
from about half-way down the Waterside Road to a little 
beyond the confluence of the Burn of Forvie. Near the 
ferry, between Denhead and the Kirkton of Logie-Buchan, 
is a considerable amount of marshy ground, intersected by 
a burn and a few ditches. Here some moderately rare fresh- 
water species were found, while near and beyond the mouth 
of the Forvie several interesting brackish-water Copepoda and 
Ostracoda were collected. The number of species obtained 
on this occasion was thirty-nine, only two of which belonged 
