Foraminiferal Limestones. 243 



I inch (19 mm.) in diameter. The form resembles a very large 

 0. dispansa, and it further resembles this species in having the 

 central area superficially studded with bosses of shell-material, 

 which are the salient ends of inverted cones pointing towards the 

 median plane. When the test is cut through tangentially these 

 conical pillars appear as fibrous shell-substance surrounding the 

 polygonal chamberlets. These cones cut longitudinally present 

 a striking appearance from their fibrous (but non - tubulate) 

 structure. 



The chambers of the median plane are of that Lepidocycline type 

 which appears as if imbricated, from the rounded ends of the 

 chambers or chamberlets being alternate with those of the adjacent 

 rows. The median series when cut through transversely is seen 

 to be quite thin in the centre and to increase greatly in 

 thickness or height towards the periphery. Another feature in 

 the chamberlets of the median plane is the presence of stolon 

 passages from one to another, thus giving a serrated appearance 

 to the inner surfaces of the walls of each chamberlet. In this 

 latter feature this species resembles the curious genus Linderina} 



Average diameter across the disc ^ inch (12'5 mm.) ; thickness 

 i inch (5 mm.). 



IText in order of succession we have No. 562, which is a pale 

 cream-coloured limestone, very compact. This is from the upper 

 cli:ff at about 500 feet. Viewed under the microscope the rock 

 is seen to consist of clear crystalline calcite, which also fills the 

 cracks appearing in various directions throughout the rock. This 

 latter fact points to some disturbance of the rock - mass after 

 consolidation. The rock is very full of organisms, consisting of 

 Lithothamnion, foraminifera (amongst which the genus Orhitoides 

 plays an important part), echinoderm plates, and polyzoa. 



The following foraminifera were observed in specimen ITo. 562 : — 



SpirolocuUna, sp. 



One or two specimens of a neat Spiroloculina occur here, but it 

 is impossible to say anything with regard to its specific relations 

 from the sections. 



Miliolina trigonula (Lamarck). 



This is quite a common form in the sections of No. 562. Its 

 relationship is clearly made out by the number of the specimens, 

 cut in various directions. 



^ See Schlumberger, Bull. Soc. Geol. France, ser. iii, vol. xxi, p. 120, 

 figs. 3-6, woodcuts ; pi. iii, figs. 7-9. 



