172 
DR. MANTELL ON BELEMNITES, ETC. 
Other organic remains which usually abound in this division of the Oolite formation, 
and among them are several unique and exquisite examples of Ammonites, Belem- 
nites, &c. Imbedded with the animal remains were large quantities of drifted wood, 
and stems and branches of trees: some of these specimens are in the state of bog- 
wood and lignite ; others are transmuted into limestone, and have the original struc- 
ture well-preserved. Trunks and branches of coniferous trees, from ten to twenty 
feet in length, and from a few inches to upwards of a foot in diameter, were abundant ; 
a few traces of the foliage of Cycadeaceous plants, and of Araucarise, were likewise 
met with. 
The geological character of the beds of Oxford Clay exposed along this railway, is 
that of a fluvio-marine formation ; that is, an accumulation of deep sea and littoral 
shells, promiscuously intermingled with the debris of terrestrial vegetables brought 
into the sea from distant lands by the agency of streams and rivers, and transported 
by marine currents into the bed of the ocean. It would be highly interesting, but 
irrelevant to my present purpose, to dwell on the geological phenomena presented by 
the sections laid bare by the operations of the engineer along this tract of ten or 
twelve miles. The great quantity of the shells of mollusks referable to species which 
dwell in the profound abyss of the ocean, collocated with those which can exist only 
in waters of moderate depths, and the intercalation of drifted trees and plants, 
formed a striking illustration of the nature of the bed of the ancient oolitic sea, strewn 
with the spoils of the land, and the exuviae of the animals with which the waters of 
that ocean were densely inhabited=^. 
As the Oxford Clay traversed by the Trowbridge line is a continuation of the beds 
that were cut through at Christian-Malford, whence all the specimens of Cephalopoda 
collected by Mr. Buv, the well-known fossil dealer of Chippenham, were procured, 
my son’s attention was particularly directed to the discovery of examples that would 
tend to elucidate the nature of the soft parts of the animal to which the Belemnite 
belonged ; for notwithstanding the memoir above referred to, doubts were entertained 
by several competent observers as to the validity of the arguments which led Pro- 
fessor Owen to assign the fossil Cephalopod, termed Belemnoteutliis antiquus by the 
late Mr. Channing Pearce, and described by him in 1842'|', to the same genus as 
the true Belemnite, and to the species named B. Owenii by Mr. Pratt. 
Care was therefore taken to remove, when practicable, the Belemnites, Ammonites, 
&c. with a large portion of the surrounding clay ; and this, when hardened by drying, 
* My son’s collection comprises very fine specimens of Ammonites Konigi, A. Calloviensis, A. sublcevis, 
A. athleta, &c. ; beautiful examples of a boat-like ammonite witb a sharp keel, A. Chamusseti ; a large depressed 
ammonite with a flat back and a single row of nodular tubercles on the wreaths ; several kinds of Nautilus ; 
numerous small shells of the genera Rostellaria, Terebra, Turritella, Trochus, &c. ; Ostrea deltoidea, Grypheea 
dilatata, Terebratula, &c. ; bones of Ichthyosauri, Plesiosauri, Teleosauri, Cetiosauri, &c. ; and a few scales and 
teeth of Ashes. 
t Geological Proceedings for 1842, vol. ii. p. 593 ; but not referred to in Professor Owen’s memoir. 
