Ostracoda and Foraminifera of Tidal Rivers. 21 
Genus CyrHERE, Müller. 
Cythere fidicula, nov. sp. 
Carapace, as seen from the side, pu height equal to 
not much more than one-third of t he length ; extremities 
narrowly rounded below, above the middle sloping steeply 
upwards to the short and straight superior margin, which 
they join at an obtuse angle ; inferior margin almost straight, 
but slightly protruded in front of the middle by a roun 
tubercular eminence. Seen from above, elongated, sub- 
hexagonal, with parallel sides and obtuse or subtruncate 
extremities ; the two anterior angles well marked, the pos- 
terior rounded off; width equal to the height; seen from 
below, the ventral surface exhibits at its anterior angles two 
prominent rounded eminences, behind which it becomes 
slightly constricted, again swelling out into a convex mar- 
gin behind the middle; the outline on this aspect is thus 
remarkably fiddle-shaped. End view triangular, apex 
rounded off, basal angles prominent and acute, sides convex, 
base concave. Shell marked with irregular and sinuous 
longitudinal rugæ, which on the concave ventral surface are 
especially conspicuous. Length 3! 
Hab. Estuaries of the rivers Thane ‘Sele and Meuse; 
very rare in all these localities. One wien has also 
occurred in a dredging from the north of cotland 
Genus CYTHERIDEA, Bosquet. 
Cytheridea torosa (Jones). (Pl. VIII. figs. 6, 7.) 
A peculiar form of this species, which occurs commonly 
throughout Norfolk and Suffolk, but has not yet been found 
in the recent state elsewhere, requires a few words of notice. 
It agrees closely with the typical fossil specimens described 
by Professor Rupert Jones, and differs from the common recent 
rm only in the presence, on the sides of the valves, of se- 
veral large rounded eminences or tubercles, which are variable 
marked example may be understood from our fignres. The 
occur bee in many localities "a ine món in com- 
pany, and both exhibit their peculiar characters in very early 
stages of growth ; but there are many grades between perfectly 
smooth specimens and the strongly marked valves represented 
in our pae We find the smooth form (C. littoralis, Brady), 
* I take this opportunity of withdrawing an opinion recently expressed. 
by me as to ‘the synonymy of | the present species, in a paper on the 
