ET meena 
Ostracoda and 2 m di Tidal Rivers. 19 
10). tx ulative organs of exceedingly complex structure, 
Dec 
ppoe (fig. 11). aros an spin rami (fig. 9) well 
developed ; two long and nearly equal terminal claws, and 
one minute seta; also from the border of the ramus, a little 
below the middle, one long slender seta. Length of female 
zs inch, of male 4; inc 
Hab. Site of Whittlesea Mere; Wroxham, Barton, and Ormes- 
by Broads. 
are identically t e: those most nearly allied are bine 
rivularis, pellucida, Taeao, and compressa, e small 
number d the imperfect peranna of their 
Genus METACYPRIS, nov. gen. 
Shell moderately strong and thick. Seen from the side, de 
€ is subrhomboidal, rounded in front, and obscur 
hind ; the posterior portion of the bingecmásgiód 
aad angularly. Seen from above, heart-shaped, ex- 
cessively tumid, widest behind the midje ventral surface 
deeply impressed along the central and posterior portions of 
the median line. Hingement formed on the n valve by 
