30 
THE ENTOMOSTRACA OF 
the Cretaceous deposits, except Speeton Clay ; it occurs also in a Tertiary Blue Clay 
at Bracklesham. 
The young form of this species is described by AL Roemer, as occurring in the 
Lower Chalk-marb at Leraforde, 
C. reniformis. Bosquet, is apparently a kidney- shaped variety of this species ; and 
it is very probable that the var. brevis of Cythere amyydaloides, Cornuel, is also identical 
with C. ovata. 
No. 2. Cytherella truncata. Bosquet. Tab VII, fig. 25 a — e. 
Cytheiuna truncata, Bosquet. Ent. foss. Maestricht, p. 7, n. 2, pi. i, fig. 2 a — c. 
YOUNG. ADULT. 
INCH. INCH. 
2’^ Gault, Folkstone andLeacou Hill. 
Chalk-marl, Dover. 
Y3- Detritus, Cliaring. 
Chalk, South-East England. 
Chalk, Maestricht {Bosquet). 
— Balsberg, Sweden. 
Length, 
Height, 
Thickness, 
Tertiary, Eocene, Alabama, North America. 
— — Barton, Hants. 
— — Colwell Bay, Isle of Wight. 
— Miocene, Bordeaux. 
Carapace oblong, closely resembling in shape the seed of the sunflower ; retaining 
the same form through all stages of growth ; occasionally constricted across the 
median third of the valves, and subject to slight variation in the curvature of the 
dorsal and ventral borders. Valves convex on the posterior half, depressed anteriorly, 
smooth and shining; faintly pitted, the punctations arranged in seven to eight 
longitudinal lines.^ Dorsal and ve^itral borders ntrccXy straight. Anterior and joosterior 
extremities somewhat rounded, the latter sometimes oblique at its superior moiety. 
The dorsal border of the right (larger) valve is more arched than that of the left, and 
the ventral border of the left (smaller) valve rather more incurved than that of the right. 
Dorsal aspect wedge-shaped ; anterior compressed oval. 
This differs from the preceding species by the carapace being smaller, narrower, 
and straighten ; by its being more strongly depressed anteriorly, and more decidedly 
truncated posteriorly. 
The Alaestricht form figured and described by AL Bosquet is more arcuated than 
the generality of individuals from the other Cretaceous deposits. This species is of 
much rarer occurrence in the Cretaceous Formation than C. ovata. The Tertiary 
specimens are by no means rare, they vary considerably with regard to the puncta- 
tions ; when the pittings are coarse, the specimens approach very nearly to 
C. aciculata, Roemer (Jahrbuch, 1838, p. 517, n. 21, pi. vi, fig. 21). 
^ This “ lower white (sandy) chalk-marl” is the lowermost bed of the chalk without flints, and super- 
incumbent on the grey chalk-marl. — See Taylor’s Scient. Mem. loc. cit. 
- This character is well shown in some of the best preserved of the Gault specimens. 
