134 E. GROVE AND G. STURT ON 



papillae, which are absent from a small circular space in the centre. 

 Two depressions in the form of clear furrows separate the central 

 portion from the ends. Length -0034" ; breadth -002". (PI. 

 X, Fig. 15.) 



B. dissipata, n. sp., Gr. and St. — Valve oval, with subacute 

 ends, convex, with a depressed clear circular space in the centre, 

 in which is a spine mounted on a small hyaline projection. Pro- 

 cesses conspicuous, inclined laterally in opposite directions, arising 

 from slightly bullate inflations, commencing near the centre. Sur- 

 face, excepting at the clear centre, dotted with small widely sepa- 

 rated puncta. Length -004" ; breadth -0026". (PI. X, Fig. 16.) 



B. vittata, n. sp., Gr. and St. — Valve lanceolate, with central 

 constriction and acute ends. On each side of the centre are two 

 transverse vittge, or septa, dividing the interior of the valve into 

 five compartments. In frustular view the compartments are seen 

 to be of nearly equal height, the processes projecting but slightly. 

 The surface is covered with large circular granules, excepting at 

 the extremities of the processes, which are finely punctate. On 

 the summits of the compartments are a few scattered spines, 

 which have disappeared in the specimen from which our frustular 

 view was figured. Length to -0045". (PI. XI, Figs. 19, 20.) 



B* tenera,n. sp., Gr. and St. — Frustule very hyaline, with central 

 depression bearing a stout spine, and an elevation or inflation on 

 each side. Processes well developed, similar in form to those of 

 B. aurita. Valve narrow, oval, with produced extremities. Surface 

 of the inflations covered with minute dots. Length '0025". (PI. 

 XIV, Figs. 56, 57.) 



B. (Cerataulus ?) rerersa, n. sp., Gr. and St. — Valve oval, 

 with broadly rounded ends and two mastoid processes placed 

 on opposite sides (as in Cerataulus turgidus, from which in other 

 respects it is distinct). In the centre is a group of numerous 

 small spines, on each side of which is a narrow transverse hyaline 

 space, the remainder of the surface being covered with exceedingly 

 fine clots. Frustular view not observed. Length -0025". (PI. 

 XIV, Fig. 62.) 



B. punctata, Grev. — Since our notice of the occurrence 

 of this species (" J. Q. M. C," Vol. ii, Ser. ii, p. 325), some 

 frustules have been found in which the conspicuous crenulation of 

 the connecting membrane (traces of which are apparent in most 

 of the valves met with in this deposit) is well shown. As this is 



