CYTHEREIS ORNATISSIMA. 21 



This is a well-defined suboblong species, with a median lobe or narrow 

 swelling, club-shaped in the young forms (PL I, figs. 73 — 75, — formerly PI. IV, 

 figs. 10 h, lOy, 10/), but becoming narrower and interrupted, or broken up 

 into a chain-like line of tubercles (see the old PI. Ill, fig. 10 h, and PI. I, 

 fig. 70), and ultimately it is obsolete or nearly dispersed (as in PI. I, fig. 69 

 =:old PI. Ill, fig. 10 a). The older or more developed individuals become also 

 more coarsely spinose at and near the margins. In some instances, as with the 

 specimens from the deep boring at Richmond, Surrey, the clavate ridge is present, 

 as loc. cit., figs. 39 and 40, but disappearing in fig. 41. 



Dr. Marsson's G. filicosta has the medial clavate ridge of G. quadrilatera, but 

 the body of the valve is more strongly squared posteriorly than in the typical 

 form. 



Localities. — -Ghalk, Norwich, Colchester, and South-east England ; Chalh-roclc^ 

 Dunstable ; Ghalk-marl, Dover ; Detritus, Charing ; Gnult, Folkestone, Leacon 

 Hill, and Godstone; Greensand, Cambridge. Very similar in the Portland Oolite 

 of Ridgway, Dorset. 



Foreign. — Ghalk-formation, North Germany, Saxony, Bohemia, &c. 



4. Cythereis ORNATISSIMA {Beuss). Plate II, figs. 1 — 7, 15, 16; and Plate IV, 



figs. 7 and 8. 



Cytheeina oenatissima, Eeuss. Verstein. bohm. Kreideform., pt. ii, 184G, p. 104, 



pi. xxiv, figs. 12 and 18 (icones mal;e). 



— ciLiATA, Beuss. Ibid., fig. 17 (icon mala). 



— ECHiNTJLATA, Williamson. Trans. Manchester Lit. Phil. Soc, vol. viii, 



1847, pi. iv, figs. 75, 76. 

 Cttheeeis ciliata, Jones. Monogr. Entom. Cret., 1849, p. 19, pi. iv, figs. 11 a 



—11 h'. 

 Ctpeidina mubicata, Beuss. Haidinger's Nat. Abhandl., vol. iv, pt. 1, 1851, 



p. 50, pi. V, figs. 12 a — c. 

 Cytheee oenatissima. Bosquet. Mem. Coram. Carte geol. Neerlande, vol. ii, 



1854, pp. 107—110. pi. ix, figs. Qa—d (and 

 var. nodulosa, pi. vii, figs. 7 a — d). 



— — Jones. G-eol. Mag., 1870, pp. 75, 76. 



— (Cttheeeis) oenatissima, Williamson. Mem. Lit. Phil. Soc. Man- 



chester, ser. 3, vol. v, 1872, 

 p. 136. 



— oenatissima, Beuss. Elbthalgebirge in Sachseu, pt. 2, 1874, p. 146, 



pi. xxvii, figs. 5, 6 a — c. 



— (Cttheeeis) oenatissima, Jones. Syst. Lists, &c., Belfast Nat. Field 



Club, vol. i, Appendix iii, 1875, 

 pp. 79 and 81. 



