:JG0 ^Ir. O. Tlioinas on 



but my cxix'ricnce wns that Entoinostraca seldom occurred 

 in those pools in wliich the water wim foul from dccuyiug 

 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, l)ot]i of Cladocera and of 

 Copepoda, in these holes, though M. arboricula was the only 

 species met with as a rule. For instance, in one liole the 

 following species were found, in addition to M. arboricola : — 

 Alona affinis, Chydoriis oralis, Cliijihrus spfutricus, and 

 Canlhocamptus ptjf/inaus, while another large hole contained 

 only C. p!/<jm(cus in abundance. On one occasion a few 

 specimens of Candona pratensis, Hartw., were met with in 

 a hole near Rurlev t- 



The most remarkable discovery, however, was made in a 

 pool at the root of a becch-trce at Burley. In this pool 

 were a number of M. arboricola, and among them were tliree 

 specimens of Tachidius brevicornis, Lillj. — two young and an 

 egg-bearing female. The occurrence of this littoral ami 

 brackish-water species in such a situation is 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, thore is a mingling of 

 marine forms with those from fresh water, 7\ bi-cvicorfiis has 

 never been found beyond the reach of salt water, though 

 T. tittoralis, Po[)pe, 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 (|uestion which might be worth investigation. 



XLIX. — On Neotropical Bats of the Geims Eptcsicus. 

 By Oldfield Thomas. 



(Published by permission of the Trustees of the British Museum.) 



The Neotropical species of the widely-spread genus Ef>tesicuii 

 are almost all membqrs of the group of which " E. Jiilairei" 

 (using for the moment the name best known for it) is typical 

 — small delicately built hats quite different from the large 

 heavily built E.fuscus of North America. The group repre- 

 s«nted Vjy the latter, however, not only goes into Cenlral 



* Bull. Sci. France Belpique, (7) xlvii. I'll:;, pp. 215-300. 

 t E. Simon, Ann. Soc. Kiituin. Franco, *( (5) vi. IS^rt, p. 41.'), nlludcs to 

 the occurrence of Ttmi/mnstix sttujnalis, \j\nn., in hollows in tree-roots. 



