A monograph of the British fossil corals - kreidefossilien.de

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CORALS FROM THE GAULT. CHAPTER VI. CORALS FROM THE GAULT. The Fossil Corals coutaiiied in the Gault are more numerous than those imbedded in the upper greensand and the lower chalk. ]\Iost of them belong to the family of Turbinolidae, and the principal localities where they have been met with in England are Folkstone and Cambridge. Family TURBINOLIDAE (p. xi). Tribe CYATHININ^E (p. xii). L Genus Cyathina (p. xii). Cyathina Bowerbankii. Tab. XI, fig. 1, \a, \b. Cyathina Bowerbaxkii, Milne Edwards and J. Haime, Monogr. Turbin., in Ann. des S'c. Nat., 3'" serie, vol. ix, p. 292, 1848. Coi'allum simple, elongated, tm-binate, very narrow, and slightly bent near the basis, which does not appear to have expanded much. Wall quite naked. Cosfce almost flat, distinct from the basis, or nearly so, covered with small granulations, nearly equal, and showing a slight tendency to form binary groups. Calice circular. Columella not nmcii developed, and composed of twisted blades. Septa forming four complete cycla; very thin, but slightly granulated, and rather unequal. Those of the last cyclum very little developed, and the tertiary ones rather thickened towards the inner edge. Pali corresponding to the penultimate cyclum of septa, and rather broad. Height of the coral, eight or nine lines ; diameter of the calice, three lines and a half. This fossil was found in the Gault at Folkstone, by our friend Mr. Bowerbank. All the specimens that we have seen were very incomplete, but some showed all the principal characters represented in the figures which we have given. C. Bowerhanhii is easily distinguished from C. Smitldi and C pseudoturbinoUa, by not having a fifth cyclum of septa. It differs also from C. arcuata by the delicacy of its septa, and from C. Guaxlulpeims by the circular form of its calice, and its round columella.
62 BRITISH FOSSIL CORALS. C. cylindrica, C.Breda, and C'.Koninckii, have only six large j!?«/«, whereas in C. Bowerhanlcii the number of these organs amounts to twelve. C. Iccvigata^ differs from the abovedescribed species, by the pali being narrow, and very thick, and C. Beheyana by the existence of a well-marked epithecal band near the calice. M. Alcide d'Orbigny has, in a recent publication," referred to this species as the type of his new genus Jmbloci/afhus, which he defines as being Cyatlnna, with a circular calice and a round columella. He adds that Amblocyathus is a lost genus, and contains three fossil species belonging to the Neocomian and Albian^ strata. We must, however, beg leave to remark, that the two above-mentioned characters are met with in almost every species of our Cyathina, and most especially in C. ci/afJius, which is the type of the genus Cyatlnna, and is actually living in the IMediterranean sea. Only two of the species referred to the genus Cyathina in our ]\Ionograph ' of the Turbinolidse' present a slightly oval calice and a transversal columella C. 2}seudoturbinoKu and C. Guadulpensis. In C. SmitJiii the columella is oblong, but the calice is circular, or nearly so. If it be con. sidered necessary to separate the Cyathina with a circular calico from those that have an oval calice, it would therefore be more proper to give a new generic name to the latter, and not to change the denomination of the group containing the very species for which Ehrenberg first established the genus Cyathina. But this innovation, proposed by M. d'Orbigny, appears to us as being in every respect unnecessary, for the slight deformation of the calice and the columella which forms the sole basis of the new generic division, can hardly be considered as characters of sufficient value; species that differ in no other respect are often found to vary in this way, and even specimens belonging to the same species sometimes differ much in the form of the calicular margin. Thus, although the calice is circular, or nearly so, in most specimens of C. cyathis and C. Sniif/iii that are met \nth, we have seen some that were compressed, and had the calice as oval as in C. pseudoturhinolia and C. Guadulpensis ; similar deviations from the normal form are also to be met with in the columella; in C. SniUJiii, for example, this organ is sometimes quite circular, although it is in general oblong. Differences of this kind, when not more marked than is the case among the various species of Cyathina, can therefore scarcely be deemed important enough to characterise generic divisions ; and, as in the present case, they do not appear to coexist with any other structural peculiarity, we see no reason for admitting the new genus Amblocyathus. 1 Tab. ix, fig. 1. 2 Note siir des Polypiers Fossiles, Paris, 1849. ^ M. d'Orbigny eniploy.s the name oi Albiuti formation to designate the Gault.
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THE PALiEONTOGRAPHICAL SOCIETY. INS
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i. E. ADLJIED, PBINTr.B, BARTHOLOME
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e 7b-^,pi'? PRINTED BY C. AND .1. A
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INTRODUCTION. iii centre of the ram
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INTRODUCTION. v certain parts of th
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INTRODUCTION. vii in which the mult
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INTRODUCTION. ix Sub-class 1. CORAL
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; INTRODUCTION. xi Sub-order 1. ZOA
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INTRODUCTION. xiii 3. Genus Acantho
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; INTRODUCTION. xv formed by proces
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; INTRODUCTION. xvii IS. Genus Plat
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INTRODUCTION. xix Aberrant Group. P
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INTRODUCTION. xxi 8. Genus Amphelia
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INTRODUCTION. xxiii 3. Genus Dkndra
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INTRODUCTION. xxv 5. Genus Ccelosmi
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INTRODUCTION. xxvii in the two prec
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; INTRODUCTION. xxix 23. Genus Pler
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; INTRODUCTION. xxxi 30. Genus Hete
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INTRODUCTION. xxxiii 30. Genm Symph
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;; INTRODUCTION. xxxv 44. Gentts Tr
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LNTRODUCTION. xxxvii 50. Genus Dipl
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INTRODUCTION. xxxix Section IV.—
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; INTRODUCTION. xli 64. Genus Astro
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INTRODUCTION. xliii which thus form
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; INTRODUCTION. xlv 79. Genus Oclan
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INTRODUCTION. xlvii 4. Genus Micbab
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INTRODUCTION. xlix 14. Genus Ctclos
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INTRODUCTION. li the sclerenchyma,
Page 63 and 64: INTRODUCTION. liii 7. Genus Stephan
Page 65 and 66: INTRODUCTION. Iv Family VII. PORITI
Page 67 and 68: . INTRODUCTION. Ivii Second Tribe
Page 69 and 70: INTRODUCTION. lix 4. Genus Fistulip
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Page 73 and 74: INTRODUCTION. Ixiii Family X. SERIA
Page 75 and 76: ; INTRODUCTION. Ixv Family XIII. CY
Page 77 and 78: INTRODUCTION. kvii 7. Gejius Hallia
Page 79 and 80: INTRODUCTION. hix 17. Genus Gonioph
Page 81 and 82: INTRODUCTION. Ixxi or costal radii
Page 83 and 84: INTRODUCTION. • Ixxiii The genera
Page 85 and 86: INTRODUCTION. Ixxv Family I. ALCYON
Page 87 and 88: INTRODUCTION. Ixxvii Second Tribe
Page 89 and 90: INTRODUCTION. Ixxix 1 7. Ge?ius Dis
Page 91 and 92: INTRODUCTION. Ixxxi 8. Genus Soland
Page 93 and 94: INTRODUCTION. Ixxxiii 3. Ge7lUS ViR
Page 95: INTRODUCTION. Ixxxv Order 3. PODACT
Page 98 and 99: CORALS OF THE UPPER CHALK. 46 towar
Page 100 and 101: CORALS OF THE UPPER CHALK. 47 Famil
Page 102 and 103: : CORALS FROIM THE UPPER CHALK. 49
Page 104 and 105: CORALS FROM THE UPPER CHALK. 51 Tho
Page 106 and 107: CORALS FROM THE LOWER CHALK. 53 CHA
Page 108 and 109: CORALS FROM THE LOWER CHALK. 55 the
Page 110 and 111: CORALS FROM THE UPPER GREENSAND. 57
Page 112 and 113: ; CORALS FROM THE UPPER GREENSAND.
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Page 118 and 119: CORALS FROM THE GAULT. 65 found nea
Page 120 and 121: CX)RALS FROM THE GAULT. G7 and have
Page 122 and 123: ' Petref. : ; CORALS FROM THE GAULT
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Page 130: TAB. IX. CORALS FROM THE UPPER CHAL
Page 138: TAB. XI. CORALS FROM THE GAULT. Cya
Page 142 and 143: 302 TABLE OF BRITISH FOSSIL CORALS.
Page 144 and 145: 304 TABLE OF BRITISH FOSSIL CORALS.
Page 146 and 147: A. GENERAL INDEX;
Page 148 and 149: 308 GENERAL INDEX.
Page 152 and 153: 312 GENERAL INDEX. Dendrophyllia de
Page 154 and 155: 314 GENERAL INDEX. . Halysites cate
Page 162: 322 GENERAL INDEX. Xenia Zaphrentis
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