D. J. SCOUEFIELD ON BRITISH CLADOCERA. 65 



curved expansion. The first foot is provided witli a strong 

 hook, and a long filament very closely resembling the flagellum 

 of the antennule. Length -j'^^in. 



The only examples I have seen were taken at Wanstead Park, 

 Essex, September, 1891. They exceeded the females in num- 

 ber in that gathering, and all the latter carried ephippia. 



It seems very probable that Baird found this form, although 

 including it with G. reticulata, for in the "Natural History of 

 the British Entomostraca " there is a drawing of a so-called 

 Daphnia reticulata (Tab. vii.. Fig. 5), having the shell striae, and 

 even the general outline of the present species. Nothing, 

 however, is said in the text about a D. reticulata with striated 

 valves. The description of D. reticulata only states that " the 

 surface is covered with a complete meshwork of small 

 hexagonal cells." 



Oeriodaphnia quadrangula, 0. F. Miiller (Plate lY, Figs. 

 4-7). — The form here referred to 0. F. Miiller's Daphnia quad- 

 rangula, is a much smaller species than the foregoing, and not 

 nearly so readily distinguished. It closely resembles a small 

 0. reticulata, but its shell-sculpture is fainter, while the tail- 

 claws are without the accessory teeth, so well marked in that 

 species. 



Female. — Very light straw-coloured or more rarely slightly 

 red. Head with a distinct bay anteriorly, and a moderate angu- 

 lation in front of the antennules. Fornices covering the bases 

 of the large antennse rather prominent, with or without a little 

 spine at their extreme lateral extension. Cervical groove deep. 

 Dorsal margin of shell well arched, with a rather sharp angle 

 posteriorly. Shell-markings nearly regular hexagons, distinct, 

 but not very strong compared with some other species of the 

 genus. Tail slightly tapering towards the extremity, which is 

 rounded dorsally. Terminal claws without accessory teeth. 

 The anal spines, numbering about ten, are stout and recurved. 

 Just anterior to the anus, and on a level with the smaller anal 

 spines, are two rows of three or four long and slender setae 

 closely approximated to the middle line of the tail. This 

 feature seems constant in all the specimens I have examined, but 

 I have not seen it referred to by previous authors. The brood 

 chamber is closed by one abdominal spur, which is followed by 



JouRN. Q. M. C, Series II., No. 31. 5 



