242 ON THE BKITISH SPECIES OP ENTOMOSTRICA " 



1850. Daphnia Schcefferi, Baird, Brit. Entom., p. 93, pl.YIL, 



figs. 1,2; pi. YIII., figs. A-I. 



1896. , , magna, Eichard, Revision des Cladoceres (Ann. 

 des Scien. Naturelles, S*" Serie, Zoologie), p. 

 192, pi. XX., fig. 1 ; pi. XXIV., figs. 6-13. 



Female. — Seen from the side the outline is broadly subovate, 

 greatest height situated near the middle and equal to about two- 

 thirds of the length ; the dorsal margin forms a flattened arch 

 with a slight depression near the middle ; ventral margin evenly 

 and very boldly convex, passing with an almost semicircular sweep 

 from its origin behind the head to the base of the posterior spine, 

 in front of which there is a slight bulge ; spine not very long, 

 generally about one-fourth or one-fifth of the length of the body, 

 and directed slightly towards the dorsal aspect. The head is 

 depressed, very small and narrow, and produced into a sharp 

 beak which projects straight downwards, the antennules forming 

 a prominence on its posterior margin. Antennules conical (fig. 

 3), the apex of each studded with a group of nine bead-like 

 papillae, from each of which springs a fine sensory filament. 

 Antennae densely clothed with short scale-like hairs. Caudal 

 laminae (fig. 4) wide in front and tapering rapidly to the extrem- 

 ity, in front of which the margin is deeply sinuated; in front 

 of the sinus is a series of 12-14 spines of nearly uniform length, 

 behind the sinus a shorter series of 6-8 rather smaller spines ; 

 terminal ungues finely pectinated ; the sides of the laminae to- 

 wards the base densely clothed with a short rigid pubescence. 

 Dorsal abdominal lobes confluent at their bases, the anterior lobe 

 very long and flexuous. Eye rather large, situated near the ante- 

 rior margin of the head. Intestinal coeca very conspicuous and 

 forming subcircular loops near the back of the head. Margins 

 of the valves smooth in front, but behind the middle fringed 

 with short spines. Shell marked with small quadrangular reticu- 

 lations, which, however, become polygonal towards the head and 

 anterior margin. Length, 4 mm. 



Male. — Outline subquadrangular, height equal to more than 

 two-thirds of the length, dorsal and ventral margins subparallel. 

 Head slightly prominent in front, its lower margin almost straight. 



