360 Mr. O. Thomas on 
but my experience was that Entomostraca seldom occurred 
in those pools in which the water was foul from decaying 
leaves. Generally, however, the water is very pure, and a 
kind of fine peat is deposited by slow decay of the leaves, as 
has been described by Picado*. Contrary to Mr. Scourfield’s 
experience, I found other species, both of Cladocera and of 
Copepoda, in these holes, though J. arboricola was the only 
species met with as a rule. For instance, in one hole the 
following species were found, in addition to M. arboricola:— 
Alona affinis, Chydorus ovals, Chydorus sphericus, and 
Canthocamptus pygmeus, while another large hole contained 
only C. pygmeus in abundance. On one occasion a few 
specimens of Candona pratensis, Hartw., were met with in 
a hole near Burley f. ’ 
The most remarkable discovery, however, was made in a 
pool at the root of a beech-tree at Burley. In this pool 
were a number of JZ. arboricola, and among them were three 
specimens of Tachidius brevicornis, Lill]j—two young and an 
egg-bearing female. ‘The occurrence of this littoral and 
brackish-water species in such a situation 1s extraordinary 
and unaccountable, since the water in these holes must be 
pure rain water, and Burley is over six miles from the sea. 
In the East Norfolk rivers, where there is a mingling of 
marine forms with those from fresh water, 7. brevicornis has 
never been found beyond the reach of salt water, though 
T. littoralis, Poppe, penetrates sometimes into quite fresh 
‘water. No chemical analysis of the water in these tree-holes 
has been made, but it is possible that it may become rather 
highly concentrated by evaporation without drainage. That 
is a question which might be worth investigation. 
XLIX.—-On Neotropical Bats of the Genus Eptesicus. 
By OLDFIELD THOMAS. 
(Published by permission of the Trustees of the British Museum.) 
‘THE Neotropical species of the widely-spread genus Eptesicus 
are almost all members of the group of which “ EZ. hilazrei” 
(using for the moment the name best known for it) is typical 
—small delicately built bats quite different from the large 
heavily built H. fuseus of North America. The group repre- 
sented by the latter, however, not only goes into Central 
* Bull. Sci. France Belgique, (7) xlvii. 1913, pp. 215-860, 
+ KE. Simon, Ann. Soc, Entom. France, (6) vi. 1886, p. 415, alludes to 
the occurrence of Tanymastiu stagnalis, Linn., in hollows in tree-roots. 
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