92 Dr. W. Baird on British Entomostraca. 



in the other genera. First pair of feet large. Eye areolar, 

 accompanying black spot nearly half the size of the eye, 

 squarish shaped. Upper part of body very rounded and cre- 

 nated round the outer edge. Intestine convoluted, having one 

 turn and nearly half another. 



Hab. Pond at Osterly Park; ditch near Richmond opposite 

 Isleworth church ; C6 pond on Beaumont water, and in Dun- 

 glass pond." — Trans. Berw. Nat. Club. 



2nd Sp. Acroperus nanus. PI. III. f. 8. 



Somewhat resembles the last in shape, but is very small, 

 not the seventh part the size, is less transparent, less deeply 

 sinuated on anterior margin and less projecting at lower ex- 

 tremity. The striae or ribs are not so large, and are disposed 

 in a waved form, obliquely transverse. Anterior margin of 

 shell ciliated. Beak rather long, sharper than in preceding 

 species. Rami slender and rather shorter than in harpce. An- 

 terior branch has four setae, one springing from the second, 

 and three from extremity of last articulation. Posterior branch 

 has three setae springing from last joint only. Tail has a gib- 

 bous projection about the middle of the lower margin, and is 

 serrated at extremity. Intestine convoluted, one turn and 

 nearly a half. One ovum. In size this species is considerably 

 less than the Chydorus sphcericus, and is about the smallest 

 of the Lyncei that I have met with. 



Hab. Pond at Norwood Green and near Southall, Middle- 

 sex. Rare. 



6th Subgenus. Alona. " Shell quadrangular-shaped, 

 striated. Rami short." 



1st Sp. Alona quadr annularis. PL III. f. 9 — 11. 



Syn. Lynceus quadrangularis, Mull. Zool. Dan. Prod. no. 2393 ; 

 Entom. t. 9. f. 1 to 3. — Monoculus quadrangulus, Linn. Gmel. 



3008. no. 61 ; Manuel, Enc. MM. vii. 733. t. 268. f. 18 to 20 



M. quadrangularis, Fab. Ent. Syst. ii. 498. — Lynceus quadrangu- 

 laris, Latreille,Hist. des Crust. 208 ; Baird, Trans. Berw. Nat. Club, 

 p. 100. — Monoculus striatus, Jurine, Hist. desMonoc. t. 16. f. 1, 2. 

 — Lynceus quadrangularis ? M. Edwards, Hist, des Crust, iii. 388. 



Shell nearly quadrangular, transparent, of a deep brown 

 colour ; strongly ciliated on anterior margin, cilia long ; stri- 

 ated or ribbed longitudinally, the striae or ribs rather distant. 

 Rami short, the setae also being short. Anterior branch with 

 four, one from second, and three from last articulation. Poste- 

 rior branch has three from last joint only. Beak rather blunt- 

 ish. Tail rather narrow, sinuated near extremity and serrated 

 for about half its length on under edge; the serrae or teeth at 

 the extremity being the longest. Terminating claws long. An- 



