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V.—Some Observations on the Zoantharia Rugosa1

Published online by Cambridge University Press:  01 May 2009

Gustave Lindström
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Extract

Professor Steenstrup, some years ago, questioned the fact as to whether the Zoantharia tabulata and rugosa, included by him under the common name of “Cyathophylla,” might be considered as true polyps. MM. Edwards and Haime in framing those great subdivisions of their “Coralliaria,” remarked their striking dissimilarity from the other Actinozoa. Professor Agassiz, in his grand monograph on the Acalephæ of North America, considers these differences so important that henceforth all connection between the above-named groups and the Zoantharia aporosa and perforata will be impossible. But besides these peculiar characteristics of the Rugosa, such, for instance, as the compact imperforate structure of the calyx and septa (the septa originating from four primary ones), the absence of costæ, the strange septal fossæ in the bottom of the calyx, the processes resembling rootlets, the transverse floors or tabulæ in the interior, which often have a cellular or vesicular structure; there is another peculiarity as yet not much known.

Type
Original Articles
Information
Geological Magazine , Volume 3 , Issue 26 , August 1866 , pp. 356 - 362
Copyright
Copyright © Cambridge University Press 1866

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Footnotes

1

Translated by the Author, from the original Swedish—“Ofversigt af Vetenskaps Academiens Forhandlingar”.

References

page 356 note 2 On the Systematic Place of the Brachiopoda and the Cysthophylla (in Danish), p. 20 1843.Google Scholar

page 356 note 3 Contrib. to the Nat. Hist, of the United States. Vol. iii. p.121.Google Scholar

page 357 note 1 With very few exceptions, as in Actinia plumosa, of Torell, the calyx of Actinozoa may be divided into two exactly similar parts by any diameter whatever. The Rugosa, on the contrary, are only to be divided into two equal parts by a line drawn along the longitudinal axis of the septal pit, or the largest of the four primary septa. M. Ludwig (in Meyer's Palæontographica, Vol. x. p. 179) has ranged some of the Cyathophylla amongst the Aporosa, and formed a distinct family of the Zaphrentinæ called Pinnatæ. Although his own figures show that their septa are developed according to a quarternary system, he presumes that the “tentacula” and the primary septa have been originally six, and considers the other great differences from the Turbinolidæ as of no value.Google Scholar

page 357 note 2 Memories, Tome iii. p. 516.Google Scholar

page 357 note 3 Leonh. and Bronn, Jahrbuch, 1842, p. 232.Google Scholar

page 357 note 4 Archives du Muséum, Vol. v, p. 404.Google Scholar

page 357 note 5 In all the specimens of Z. rugosa these “costæ” alternate with the septa, there is no immediate continuation of these through the walls of the calyx as in the Z. aporosa and perforata. On the exterior wall the furrows between the longitudinal folds are opposite the septa. As above described in Goniopllyllum two or three broad longitudinal folds or striæ are also seen, in most of the Rugosa, to divide the longest side of the shell in two similar parts and to form a ridge, which, as I shall endeavour to demonstrate, is homologous with the pseudo-deltiditun of Calceola. The largest septum (or the septal-pit as seen in so many of the Zaphrentinæ) is situated on the interior wall opposite the furrow between these larger median folds. The smaller folds converge towards these median ones in a very acute angle, and the whole thereby takes a pinnate arrangement, as J. Hall has described it in Streptelasma corniculum (Pal. of New York, Vol. ii. p. 111), and F. Roemer in S. europæum (Foss. Fauna von Sudewitz, p. 16); see also Ludwig.Google Scholar

page 358 note 1 Such root like processes distinguish no less than eleven genera of the Cyatlwphyllinie, namely: Cyathophyttum, Goniophyllmn, Omphyma, Chonop/iyllum, Ptychophyllum, Heliophyllum, Acervularia, Eridophyllttm, Mhizophyllum, Axophyllum, and several Cystiphylla. These rootlets either project from the convex side of the shell, or are fixed all round it. Sometimes they have coalesced and are flattened into broad curved hooks (‘crampons,’ M. Edw.). Amongst the true Anthozoa the genera Flabettum and Rhissolrochus alone have anything analogous. The description of the rootlets of the Goniophyllum can be applied to all the above cited genera, but they are perhaps not so remarkable in any one as in the new genus Rhizophyllum, about to be described.

page 358 note 2 The term ‘septum’ is here used, without being considered homologous with the parts so named in the Actinozoa. In the same manner ‘cardinal-margin’ is used without indicating homology with the cardinal margin in the Mollusca.

page 358 note 3 See Edwards and Haime, Brit. Foss. Corals, Plate 67, fig. 3a.

page 359 note 1 This Prof. S. Lovèen has found to be the case in Coitus quadrieornis, Idotea entomon, etc., and I have myself ascertained the fact in Paludinella baltica, Nilsson.

page 361 note 1 On the development and the floating cells of the marine Broyzoa,—”Ofversigt af ret. Akad. Forhandlingar, 1865, p. 29.Google Scholar