IS 



THE ENTOMOSTRACA OP 



No. 4. Cythereis triplicata, Rcemer. Tab. Ill, fig. 9 a — h. 



Cythekina tkiplicata, Rcemer. 1840. Verstein. Ej-eidebirg, p. 104, n. 3, pi. xvi, fig. 16. 

 Cythere aueiculata, Cornuel. 1846. Mem. Soc. Geol. de France, sec. ser., torn, i, sec. part., 

 p. 200, n. 3, pi. viii, figs. 14-16. 



INCH. 



Length, Jj^ Gault, Folkstone and Leacon Hill. 



Height, Jj- Detritus, Charing. 



Thickness, Jj ChalJi, South-East England. 



Hils-clay, North Germany {Reenter). 



Inferior Greensaud, France {Cornuel). 



Carapace ovate. Valves strongly convex, especially on ventral half; very finely 

 punctate and hairy ; bearing three longitudinal, convex ridges, three fourths the 

 length of the shell, barely meeting posteriorly, free anteriorly ; the lowest ridge the 

 longest, the middle one the shortest ; the dorsal and the central ridge smooth and 

 not punctated, the ventral ridge coarsely pitted. Central tubercle large, forming the 

 anterior extremity of the middle ridge. Anterior extremity of the valve semicircular, 

 shelving abruptly to a flat lip, extending across the valve, and occupying a fourth of 

 its length. Posterior extremity shelving, contracted, subacute. 



Dorsal and ventral aspects subovate ; the latter marked with three or four coarse, 

 longitudinal wrinkles. Anterior aspect triangular. 



This species occurs in the Gault, the Charing Detritus, and the Chalk ; but is not 

 at all plentiful. M. Rcemer describes it as occurring in the Hils-clay of Hilse. In 

 the Bohemian Chalk-marl there is a nearly allied form, C. semiplicata, Reuss (Op. cit. 

 p. 104, pi. xxiv, fig. 16), and there are others in the Maestricht Chalk, viz. C. Forsteriana, 

 Bosq. (Op. cit. pi. ii, fig. 4), C. pulchella, Bosq. (Op. cit., pi. ii, fig. 5), and C. eleyans, 

 Bosq. (Op. cit., pi. iii, fig. 1) ; another of very similar characters is found in the Forest- 

 marble. 



No. 5. Cythereis quadrilatera, Boemer. Tabs. Ill and IV, fig. 10 a—j. 



Cytherina acADRiLATERA, Rcemer, 1840. Verstein. Kreideb. p. 105. n. 7, pi. xvi, fig. 19. 

 — ORNATissiMA, bis, Reuss. 1845. Verst. Bohm. Kreid. p. 104, n. 12, pi. sxiv, 

 fig. IS. 

 Cythere Harpa, Cornuel. 1846. Mem. Soc. Geol. de France, sec. ser., torn, i, sec. part., p. 199, 

 n. 2, pi. viii, fig. 13. 



YOUNG. IMMATURE. ADULT. 

 INCH. INCH. INCH. INCH. 



Length, -^ 



3-V 



A 



Height, ^ 



1 



5 



1 



Thickness, ^i^ 



^V 



^v 



Gault, Folkstone and Leacon Hill. 



Detritus, Charing. 



Chalk, South-East England. 



Inf. Greensand, France {Cornuel). 



Chalk-marl and Chalk, Bohemia 



{Reuss) . 



Chalk, North Germany {Rcemer) . 



Chalk, Weissbohla, Saxony. 

 Upper Oolite, Dorsetshire. 



Carapace irregularly oblong. Valve depressed, smooth, shining, hairy. Anterior 



extremity obhquely rounded, ha^'ing a flattened lip, longest in young individuals, with 



