46 TERTIARY ENTOMOSTRACA OF ENGLAND. 



4. Cttherideis gracilis (Eeuss). Plate I, fig, 12. 



CxTHERiNA GEACiLis, Eeuss. Haidinger's Nat. Abh., vol. iii, 1850, p. 52, pi. liii, 



fig. 3. 

 CTinEEiDEis — Brady. Trans. Zool. Soc, vol. v, 1866, p. 367, pi. Iviii, 



figs. 1 a — d. 

 — — Jones f Sherborn. Geol. Mag., 1887, p. 457. 



To this neat form, already described by Reuss and others, the following are 

 more or less allied : — C. [Bairdia) arcuata. Bosquet (' Entom. Tert.,' 1852, p. 32, 

 pi. i, fig. 14) ; C. {Bairdia) lithodomoides, Bosquet (Ibid., p. 36, pi. ii, fig. 3) ; C. 

 {Bairdia) difficilis, Reuss (' Sitzungsb. k. Ak. Wiss. Wien,' vol. Ivii, 1868, p. 85, 

 pi. V, fig. 7). 



The figure given in the ' Fonds de la Mer' (8vo., Paris, 1867-71), livr. 4, 

 1868, p. 94, pi. xii, figs. 1, 2, of Brady's Aglaia pulchella, reminds us of this form. 



"We have seen one small specimen from a Tertiary bed at Colwell Bay. In 

 the closed carapace the right valve is the smallest ; it is faintly toothed on the 

 anterior margin. The longitudinal lines on the ventral surface are distinct, 

 though faint. (British Museum.) 



C. gracilis is not uncommon in some Tertiary formations on the Continent, 

 and has many allies. 



5. ? Cytherideis unisulcata, Jones. 



Monogr. Tert. Eutom., 1857, p. 48, pi. iv, fig. 10. 



This doubtful species occurred with Gandona Forhesii in the Osborne series at 

 Cliff End, Colwell Bay. It may be a young Gypridea sjpinigera badly preserved, or 

 possibly a Metacypris. (British Museum.) 



6. ? Cttherideis ren, Jones. 



Monogr. Tert. Entom., 1857, p. 51, pi. iv, figs. 5 a, b. 

 From the Crag. The generic relationship is doubtful. (British Museum.) 



