SPIROLOCULINA PLANULATA. 



10:3 



examples, though subject to modification and interchange. Thus : — 1. Those that 

 have the surfaces of the chambers fiat (planulate). 2. The surfaces of the chambers 

 sloping down towards the centre of the shell (excavate). 3. The outer margin or 

 periphery channelled, being bordered by two limbate edges (canaliculate). 4. The 

 chambers bordered by raised lines or ridges (limbate). 5. Chambers convex on 

 surface (rotundate). 6 & 7. Other forms, not here dealt with, either (6) have the 

 surfaces of their chambers raised and ridged (angulate) ; or (7) have them sunken 

 and concave (hollow-chambered). 



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Fig. 1. — Spiroloculina planulata (Lain.). Diagram representing a transverse 

 section of the flat whorls of the shell. 



Figs. 2 a, 2 b. — Spiroloculina excavata, d'Orb. Diagrams showing the surfaces 

 of the whorls (a) sloping inwards on each surface to the hollow centre of 

 the shell j and (b) sinking by steps into the hollow of the centre. 



FlGS. 3 a, 3 b. — Spiroloculina canaliculata, d'Orb. Diagrams showing the 

 concave (channelled) outer margin of the whorls ; in Fig. 3 b the surface- 

 margins of the chambers are somewhat limbate. 



FrG. 4. — Spiroloculina dorsata, Reuss. Diagram of a transverse section of the 

 whorls with superficial shell-growth at the outer margin of each whorl, 

 marking the sutures of each face. 



p I& . 5. — Spiroloculina nitida, d'Orb. Diagram showing the convex surfaces of 

 the whorls. 



6 (^]Cy ^OQOOOO FlGl 6.— Spiroloculina, section of, with whorls having an angular surface. 



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Fig. 7. — Spiroloculina, section of, with the whorls concave on the exterior 

 surfaces. 



1. Spiroloculina planulata (Lamarck), 1804. PL III, figs. 37, 38 ; Woodcut, fig. 1. 

 Part I, 1866, page 15; and Appendix II, Table No. 15. 



Miliolites planulata, Lamarck, 1804-. Ann. Mus., vol. v, p. 352 ; 1822, Anim. 



sans Vert., vol. vii, p. 612 (three 

 varieties are indicated by Lamarck). 



Spiroloculina depressa, d'Orb., 1826. Ann. Sci. Nat., vol. vii, p. 298, No. 1; 



Modele, No. 92; Parker, Jones, and 

 Brady, 1865, Ann. Mag. Nat. Hist., 

 ser. 3, vol. xvi, p. 33, pi. i, fig. 6 ; and 

 ser. 4, vol. viii, 1871, p. 248, pi. viii, 

 fig. 23 ; referred to Sp. planulata. 



— perforata, Bronn, 1838. Letba>a Geognostica, p. 1143, pi. xlii, 



fig. 33. 



— Badenensis, d'Orbigny, 1846. Foram. Foss. Vien., p. 270, pi. xvi, 



figs. 13—15. 



— dilatata, d'Orbigny, 1846. Ibid., p. 271, pi. xvi, figs. 16—18. 



