CYTHEREIS ORNATISSIMA. 23 



4*. Ctthereis oenatissima (Beuss), var. paupera, no v. (vel ornatissima-paupera). 



Plate II, figs. 10 and 11. 



Fig. 10. Length I'O; height "55 mm. 



rig. 11. „ -82; „ -4 „ 



Small and poor varieties or ill-developed forms of C. ornatissima, with the 

 normal subcentral tubercle and smaller irregular swellings behind it, also a well- 

 marked front hinge and angular ventral ridge. The marginal edges are more or 

 less spinose, and traces of spines occur here and there on the surface, as well as 

 an imperfect reticulation on some specimens. 



Locality. — Chalk-roch, Dunstable. 



4**. Ctthereis ornatissima (Beuss), var. nuda, nov. (vel ornatissima-nuda) . Plate 



I, fig. 76; Plate II, figs.^ 9, 12—14; Plate IV, fig. 14. 



CxTHEEEis COENTJTA (noD Bmiier), Jones. Monogr. Entom. Cret., 1849, p. 21, pi. v, 



figs. 13 a — e (fig. 13ffl is nil, having 

 been wrongly drawn). 



Ctthebe oenatissima, var. Jones. Geol. Mag., 1870, pp. 75, 76. 



PI. I, fig. 76. Length 76; height -44 mm. 



PI. II, fig. 8, and PL IV, fig. 14. „ "94; „ -5 „ 



PI. II, fig. 9. „ -72; „ -33 „ 



PL IV, fig. 12. „ -91 ; thickness '38 mm. 



PL IV, fig. 14. Height -5 ; „ -33 „ 



A simple, suboblong Cythereis ; obliquely rounded, rimmed, and denticulate in 

 front ; depressed and angular at the posterior margin ; straight on the ventral 

 edge, with a smooth ridge ; the dorsal edge roughened, and having a terminal 

 angle corresponding with that of the ventral border. A subcentral round knob 

 has a smaller oval tubercle behind it, and the rest of the surface is naked and 

 smooth. This might be taken, at first sight, for G. quadrilatera, but its greater 

 height (breadth) at the anterior third, and the posterior angles of the upper and 

 lower margins distinguish it. 



In general characters this is near to G. fullonica, Jones and Sherborn, the 



* Fig. 8 is to be disregarded. The old fig. 13 a was wrongly drawn and reduced by mistake. It 

 is reproduced correctly in PI. IV, fig. 14. 



