132 BRITISH ENTOMOSTRACA. 



cilia long ; striated or ribbed longitudinally, the ribs 

 rather distant. Beak rather blunt. Eye areolar. 



Superior antennae conical-shaped ; inferior, or rami 

 (t. XVI, f. 4 b), short, the setse also being short ; anterior 

 branch having foiu", one from second and three from last 

 articulation; posterior branch has three from last joint only. 



Upper part of body rounded, as in Acroperus harpcB. 



Abdomen (t. XVI, f. 4 c) rather narrow, sinuated near 

 extremity, and serrated for about half its length on the 

 under edge, the serrae or teeth at extremity being the 

 largest. Terminating claws long. 



Intestine convoluted once, and nearly a half, but not 

 so distinctly visible as in the other genera.* 



Hab. — Ditch near Richiuond ; pond at Osterly Park ; 

 and near Hounslow. In the Pease-burn, Cockburnspath. 

 Pool on Bowmont Water, Yetholm, Roxburghshire. 



2. Alona reticulata. Tab. XVI, fig. 3. 



Alona reticulata, Baird, Ann. and Mag. Nat. Hist., ii, 93, t. 3, f.l2, 

 18i3 ; Trails. Berw. Nat. Club, ii, 151. 



In size this is perhaps the smallest of all the species of 

 this family, being still smaller than the Acroperus nanus. 



Shell of a quadrangular shape, rounded a little poste- 

 riorly, and nearly straight on anterior margin, which 



* I had some doubts at first as to this being identical with the Monoculus 

 striatus of Jurine. In his figure the beak is blunter, and the abdomen 

 shorter and rounder-shaped than in nij specimens. He gives it the name 

 striatus with a doubt ; and remarks, " if this species be the truncatus of 

 Miiller, as we may presume it is, it must be confessed that its specific name 

 is improper; for the shell is not truncated, it is obliquely striated and 

 strongly ciliated" (1. c, p. 154). It is evident that Jurine could never have 

 seen the truncatus of Miiller, and the quadranf/ularis seems also not to 

 have been known to him ; for the dift'erence between this species and the 

 truncatus is so great and evident, that they cannot be mistaken for each 

 other ; wliile the similarity between it and the quadrangularis is so decided, 

 that notwithstanding the slight discrepancies mentioned above, I have now 

 little or no hesitation iu referring them both to the same species. 



