Dr Fleming on the British Testaceous Annelides. ^41 
13. D. cylindricum — “ Cylindrical, or scarcely tapering, nearly straight, 
smooth ; aperture rounded.” Sower. Min. Conch, ib. fig. 2. In ochraceous 
sandy ironstone, near Exmouth, Mr Cunnington. In sandpits at Emsworth, 
common, Mr Sowerby. 
About three-fourths of an inch long, and almost a line in diameter ; the 
smaller end nearly as large as the other. 
14. D. incrassatum — “ Very tapering, curved, smooth, swelled near the 
aperture ; aperture round, lip sharp.” Sower. Min. Conch, ib. fig. 3, 4. Clay 
at Highgate and Richmond, Mr Sowerby. 
This seems likewise to have been a gregarious species. 
15. D. medium. — “ Shell tapering ; mouth round ; lip sharp ; tube somewhat 
trumpet-formed within, or broad at the mouth, and becoming suddenly small ; 
external transverse striae or lines of growth conspicuous.” Sower. Min. Conch, 
ib. fig. 5, G. From the green sand at Blackdown, Miss E. Hill. 
IG. D.indistinctum. — Shell about 2^ inches long, and nearly half an inch in 
diameter. The surface, where entire, is smooth, dull, and of a whitish colour. 
It consists of several layers, the surfaces of which have a shining, mother-of- 
pearl aspect. Plate IX. Fig. 2. In the limestone of the coal formation West 
Lothian. 
The general characters of the limestone in which this shell is imbedded, I 
have noticed in the Annals of Philosophy, vol. v. p. 118. ; and in the 
same volume there is a description of the following species of Ortho- 
cera: — pyramidalis.^ cylindracea.^ convexa., annularis.^ and rugosa.^ from the 
same station. The species of Product!, which Mr Sowerby has figured 
under the titles, longispinus., Flemingii., spinulosus^ spinosus., and Scoticus.^ 
are likewise of cotemporaneous origin. The same limestone likewise con- 
tains examples of nearly all those species of fossil shells and zoophytes 
which are figured in the History of “ Rutherglen and Kilbride,” by the 
late Rev. David Ure, Glasgow, 1793. This work, I may here observe, 
contains an accurate enumeration of the principal fossils belonging to 
the Independent Coal Formation of Scotland. 
Specimens of this Dentalium were sent to the late Mr Sowerby in 1814; 
but he delayed giving a figure of the species in his Mineral Conchology, 
in expectation of receiving more satisfactory examples. I have likewise 
recently communicated a specimen to Lewis Weston Dillw}^, Esq. 
All the specimens are much bruised, and, by belonging to a species des- 
titute of much character, from the simplicity of its external form, it is 
impossible to fix definite specific marks. In such circumstances, the 
geognostical relations of the species acquire great importance, and ought 
to be cautiously established. This, indeed, appears to be the oldest species 
of the genus yet ascertained, as may be seen by the following tabular 
view of the genealogy of the genus, which is offered with considerable 
hesitation : 
Independent Coal Formation. 
Dentalium indistinctum, No. 16. 
Lias ? 
Dentalium cylindricum, 13. 
Green-sand. 
Dentalium medium, 15. 
— septangulare, 8. 
Chalk. 
Dentalium ellipticum, 11. 
'■ ' - decussatum, 6. 
London Clay. 
Dentalium nitens, 9. 
entaloides, 10. 
-striatum........ 5. 
costatum, 7» 
planum, 12, 
incrassatum, 14. 
