PLEUROXUS. 
279 
Hab. Ponds and ditches in Scotland and England. 
Acropertjs nanus, Baird. — Not a seventh part the size 
of the preceding. 
Hab. Pond at Norwood Green, and near Southall, Mid- 
dlesex. 
Gen. 152. ALONA, Baird . 
Shell quadrangular, striated longitudinally. Lower an- 
tennse short. Beak blunt and nearly erect. 
Alona quadrangularis, Miiller, sp. — Shell transparent, 
deep-brown. 
Hab. Ponds and ditches. 
Alona reticulata, Baird. — A very small species, with a 
closely reticulated shell. Eound by Dr. Baird in a pond near 
Southall. 
Alona oyata, Baird.— Ovate, transparent, larger than A, 
quadrangularis . 
Hab. Pond on Blackheath. 
Gen. 153. PLEUEOXUS, Baird* 
Pront margin prominent on upper part ; lower part trun- 
* IIA evpov, a side, and sharp. 
