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| Keywords: The Quarterly journal of the Geological Society of London (12893450103).jpg Yol 53 ME A C SEWARD Otf CYCADEOZDEA GIGANTEA <br> 23 <br> are less clearly shown than in the other portions of the stem A <br> short distance above the base the preservation is particularly good <br> and much of the internal structure of the peripheral tissues is fairly <br> well preserved A transverse section has an elliptical outline fig 2 <br> Pig 2 ” Transverse section of the stem of Cycadeoidea gigantea <br> sp nov <br> measuring 41 cm along the greater diameter and 19 cm along the <br> smaller The section as drawn in fig 2 is taken from about the <br> middle of the stem ; one side is almost flat while the other has <br> a more distinctly convex form The present shape of the stem is <br> no doubt largely the result of pressure but it is possible that the <br> trunk was originally rather broadly oval than circular in section <br> Covering the surface of the specimen there is the characteristic <br> Cycadean armour of the persistent bases of spirally-arranged leaf- <br> stalks Among recent Cycads the majority of species present an <br> appearance practically identical with that of the fossil but in a few <br> living forms the surface of the stem has a very different appearance <br> the regular petiole-bases being replaced by irregular transverse <br> ridges and corky protuberances This less known and more un- <br> common form is well illustrated by such plants as Zamia STcinneri <br> Warsz Z Loddigesii Miq and several others 1 In most Cycads <br> however after the fronds have withered they become detached and <br> the lower portion of the petiole remains for a longer time on the <br> stem ; finally the ragged petiole is cut off by a clean surface covered <br> with corky tissue The surface of the old stem in certain recent <br> genera is thus covered with the regularly-disposed persistent bases <br> of the large leaves In the genus Cycas the stem shows a distinctly <br> marked alternation of large persistent bases of fronds and smaller <br> bases of old bud- scales ; while in such a genus as Encephalartos the <br> bases of bud-scales and fronds present no such regular alternation <br> and cannot be readily distinguished in the older portion of a large <br> stem The surface of the fossil trunk is completely covered with <br> rhomboidal leaf-bases approximately of the same size and it is <br> impossible to draw any definite distinction between those of bud- <br> scales and the larger foliage-leaves <br> 1 See A C Seward 'Annals Bot ' vol x no xxxviii 1896 p 218 pi xiv <br> £gs 1 2 36028728 111130 51125 Page 23 Text 53 http //www biodiversitylibrary org/page/36028728 1897 Geological Society of London NameFound Cycadeoidea gigantea NameFound Cycas NameConfirmed Cycas EOLID 53639 NameBankID 2663718 NameFound Encephalartos NameConfirmed Encephalartos EOLID 11422166 NameBankID 2663715 NameFound Gigantea NameConfirmed Gigantea EOLID 91906 NameBankID 4549793 NameFound Zamia NameConfirmed Zamia L 1763 EOLID 11421944 Biodiversity Heritage Library The Quarterly journal of the Geological Society of London v 53 1897 Geology Periodicals Smithsonian Libraries bhl page 36028728 dc identifier http //biodiversitylibrary org/page/36028728 smithsonian libraries Information field Flickr posted date ISOdate 2014-03-03 Check categories 2015 August 26 CC-BY-2 0 BioDivLibrary https //flickr com/photos/61021753 N02/12893450103 2015-08-26 17 53 44 cc-by-2 0 PD-old-70-1923 The Quarterly journal of the Geological Society of London 1897 Photos uploaded from Flickr by Fæ using a script | ||||
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