Observations on belemnites, and other fossil remains of Cephalopoda, discovered by Mr. Reginald Neville Mantell, C.E. in the Oxford clay near Trowbridge, in Wiltshire / by Gideon Algernon Mantell.

  • Mantell, Gideon Algernon, 1790-1852.
Date:
1848
Catalogue details

Licence: Public Domain Mark

Credit: Observations on belemnites, and other fossil remains of Cephalopoda, discovered by Mr. Reginald Neville Mantell, C.E. in the Oxford clay near Trowbridge, in Wiltshire / by Gideon Algernon Mantell. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    The outline, Plate XIV. fig. 1, is intended to convey an idea of the form of the animal of the Belemnoteuthis, so far as the fossils hitherto discovered warrant the restoration; of course this sketch is only approximative, and is given as a mere ♦ diagram of what is actually known as to the shape and structure of the original, and not as an accurate delineation of the living animal; for there are strong reasons to conclude that the phragmocone was wholly internal, or at least was covered by the skin. The above is, I believe, a correct description of the Belemnoteuthis, and of the form and relations of the several parts of its structure: it is based on the specimens described and figured by Mr. Channing Pearce, Professor Owen*, and Mr. Cun- nington'I', and others in my possession. Now in order to connect the body of the Cephalopod above described with the elongated conical fossil commonly known as the Belemnite, and termed by natural- ists the guard or osselet of the same, it has been assumed that the terminal chambered cone of the former (Plate XIII. figs. 2, 3, 5) was originally implanted in the alveolus or cavity of the latter; like the unquestionable phragmocone of a Belemnite, repre- sented in Plate XV. figs. 4, 5, a, a. It follows, if we admit the correctness of this interpretation, that every example of the chambered conical shell of a Cephalopod, found in the Oxford Clay, is the phragmocone of a Belemnite that has slipped out of the alveolus of the guard, and been compressed into its present shape by the weight of the superincumbent strata. Upon the correctness of this supposition the generic identity of the Belemnoteuthis and the Belemnite entirely rests; for no specimen has yet been met with, in which the guard of a Belemnite is in natural contact with the muscular mantle, and other soft parts. If the phragmocone of the Belemnite, and the chambered shell of the Belemnoteuthis be not identical, then we know nothing whatever, from actual observation, of the soft parts of the animal to which the Belemnite belonged: to this point therefore I would first solicit particular atten- tion. Phragmocone of the Belemnoteuthis.—As the figures in the Philosophical Transac- tions, 1844, Plate III., &c., and in the London Geological Journal, Plate XV. XVI., show the phragmocone in natural connection with the muscular tunic or mantle, &c., I need not adduce further examples of this undisputed fact, and will therefore only remark, that such specimens are of rare occurrence : in most instances, the detached chambered shell, more or less flattened, is found imbedded in the clay, with but few, if any, vestiges of the soft parts, as in Plate XIII. figs. 1,2, 3, 5. In this state, these fossils occurred by hundreds on the newly-exposed surface of the Oxford Clay near Trowbridge. My son describes some areas when first laid bare by his labourers, as being literally spangled over with the nacreous cones of Belemnoteuthes, and the splendid iridescent shells of Ammonites; while here and there Belemnites of large size, with their phragmocones attached, were lying in relief. Upon drying, the thin * Philosophical Transactions, 1844, p. 77-80, Plates III. IV. V. VI. t London Geological Journal, Plates XV. XVI.