ON BOSMINIDiE, MACEOTHEICID^, ETC. 367 



abdomen is usually so hidden by the feet that it is difficult to 

 detect its true form and character. Length, iVth of an inch. 



The peculiar plates attached to the ventral margin of Latlionura 

 rectirostris, instead of the usual setae or spines, at once serve to 

 distinguish this species from all other Entomostraca with which 

 we are acquainted. The abdominal setae are very easily broken 

 off; and a specimen in which they have been thus abraded is 

 figured by Leydig as the type of his Pasithea lacustris. 



Found by GL S. B. in Lough Bollard, Connemara. It has a 

 continental range extending through Russia, Germany, Norway, 

 and Sweden. 



Genus. ACANTHOLEBERIS, Lilljebory. 



Carapace somewhat oblong, truncate posteriorly, ventral margin 

 edged with long setae, which posteriorly become greatly developed, 

 and are plumose. Anterior antennae strap-shaped, widening to 

 the truncated extremity, large, and conspicuous, porrected from 

 the front of the head. Posterior antennae having the three-jointed 

 ramus furnished with five setae, and the four-jointed ramus bear- 

 ing only three setae at the termination ; lowest seta of the three- 

 jointed ramus the longest, and differing from the rest in structure. 

 Eye-spot small. Abdomen large, deep, strongly spined on the 

 edge, terminal claws of considerable size. Intestinal canal simple 

 at first, but forming a loop near the anus. Labrum with a con- 

 spicuous spine-formed process in front. 



AcANTHOLEBERIS CTJEVIKOSTEIS, (Mutter.) 



Acantlwleberis curvirostris, Norman. Ann. Nat. Hist., Ser. 3, 

 Vol. XI (1863), PL XI, figs. 1-5 ; and Trans. Tyneside 

 Nat. Eield Club, Vol. VI, p. 53. PI. VI, figs. 1-5. 



This species has already been fully described and figured in our 

 local Transactions by one of the authors of the present paper. It 

 is only necessary therefore to refer the reader to the sixth volume 

 of the Transactions of the Tyneside Naturalists' Field Club. 



Acantlwleberis curvirostris delights in peaty water, and would 

 appear to be far from rare on the moors of the British Islands. 



