British Freshwater Entomostraca. 359 
with Dr. Scott’s description and figures of C. hirticornis 
leaves no doubt that both were dealing with the same 
species. As Schmeil’s name has priority, it is unfortunate 
that the specific name of hirticornis must give way to that 
of rapiens. Prof. Sars is undoubtedly right in including 
the species in the genus Mesochra. 
Mesochra rapiens is fairly common’ in the Norfolk Broads, 
where the salinity is high (e. g., Hickling and Horsey), and 
I have also found it at Flordon Common, near Norwich. 
The water there is perfectly “‘ fresh,” but is highly calcareous, 
and my specimens were found in greyish calcareous mud, 
covered only by a mere film of water. It occurs also in 
Oulton Broad, in Suffolk, since a slide in Dr. Brady’s 
collection, labelled ‘‘ Canthocamptus palustris, Oulton Broad,” 
contains, besides several C. palustris, also two specimens of 
Mesochra rapiens and one of Tachidius littoralis, Poppe. 
This slide was probably made before the year 1880. 
M. rapiens has been found by Dr. Scott in various parts 
of Scotland (Outer Hebrides, Loch Tarbert, Forth District, 
Loch Lomond, and R. Ythan, Aberdeenshire), often in 
brackish water and always not far from the sea. In the 
Baltic it has been recorded from Colberg by Schmeil in water 
of a salinity of *5 °/., and by Lilljeborg from the Baltic coast 
and from the Ekoln branch of Lake Malaren in fresh water. 
Prof. Lilljeborg suggests that it may be regarded as a relict 
in Lake Malaren of a former extension of the Baltic. The 
Ekoln is known to contain other Crustacea which are supposed 
to be relicts of such former extensions*. In Norway the 
species has only been taken in a brackish pool in the South. 
6. Tachidius brevicornis, Lillj., in fresh water. 
Mr. Scourfield { has drawn attention to the small pools 
of water which collect at the roots and in holes in trees as 
the habitat of Entomostraca, and has described a new 
species, Moraria arboricola, which inhabits such pools in 
Epping Forest. In Epping Forest the pollarding of the 
oaks has provided innumerable water-holes, but I found, 
during a visit to the New Forest in August 1919, that the 
only collections of water there were in beech-trees, either at 
the roots or in the hollow in the fork between two main 
branches, though there were other holes which had at one 
time contained water, but were then dry. Moraria arboricola 
proved to be common, occurring in the majority of the pools, 
* Ekman, Zool. Stud. tillign. T. Tullberg, 1907. 
t Journ. Quelett Mic. Club, (2) xii, 1915, p. 4381. 
