48 TERTIARY ENTOMOSTRACA OF ENGLAND. 



many of the Cytherellse here described have been obtained. (All the above are in 

 the British Museum.) 



A very small Cytherella, smooth, subovate, and with lanceolate edge-view, 

 belongs apparently to Group II; PI. Ill, figs. 25 a, h. It was found by Mr. 

 Clement Reid in the Weybourn Crag of Bast Runton. (Mus. Pract. Geol.) 



Gkoup III. — The type of this group is Cytherella Betrichi (Reuss). 



Cytheeina Betiucui, Reuss. Zeitschr. deutsch. geol. Ges., vol. iii, 1851, p. 89, 



pi. vii, fig. 65. 



— — Bornemami. Ibid , vii, 1855, p. 354, pi. xx, fig. 1. 

 Cytherella compeessa, var. 1, Jones. Monogr. Tert. Entom., 1857, p. 55, pi. v, 



fig. 18. 



— Beyeichi, Speyer. Ostrac. Cassel. Tertiar., 186.3, p. 5-1, pi. i, fig. 1. 



— — Bradi/. Trans. Zool. Soc, vol. v, 1866, p. 362, pi. ivii, 



fig. 3. 



— — Jones. Geol. Mag., 1870, vol. vii, p. 157. 



— — Jones ^- Sherborn. Geol. Mag., 1887, p. 458, pi. si, fig. 18. 



In this group the cai'apaces vary from round-ended oblong to ovate-oblong, 

 with a flattening of the anterior portion, giving a wedge-shaped edge- view. The 

 posterior end is full and more or less truncate, herein also differing from the 

 members of Group II. Generally the surface is pitted, but we have a smooth 

 example of this form (PI. II, figs. 1 a, h). The last has been termed 0. Betrichi, 

 var. L.^vis (' Geol. Mag.,' 1887, p. 458) ; but we consider that the others (PI. II, 

 figs. 2 a,h ; b a, b; 6 a, b ; 7 a, b ; 9 a, b) do not offer differences sufficient to 

 separate them from the type as named varieties. Fig. 9 a, however, is more ovate 

 than oblong ; and 9 b shows a very definitely truncate posterior, giving the edge- 

 view a more strictly triangular appearance. (British Museum.) 



Note. — A small indeterminable CijfhereUa occurs among some Ostracoda collected 

 by the late Mr. F. E. Edwards from the Fluvio-marine beds of Headon (?). 

 (British Museum.) 



In the annexed Table the genera and species belonging to each Geological 

 Formation are arranged, in their several groups, in the same order as that adopted 

 in the Lists at pp. 3 — 8. The localities for the specimens will be found in the 

 text of either the original or the Supplemental Monograph, the pages being easily 

 referred to. In the Classified Lists (pp. 3 — 8) the different stages of the Eocene 

 Formation are indicated by the addition of local names, as Woolwich, London, 

 Bracklesham, &c. The indication of foreign localities for the Tertiary Euto- 

 mostraca is not now attempted, for much closer examination will be required to 

 ensure anything like accuracy in this direction. 



