Dentalium. 
ANNELIDA. 
243 
Family II.—MALDANLE. 
Branchice of the animal intermediate; tube open at both ends. 
Genus III.—D E N T ALIU M.— Lin nanus. 
Shell tubular, open at both ends, arcuated, increasing in 
diameter towards the anterior extremity, where the aperture is 
large and round; opening of the pointed end very small, and 
with a lateral fissure in some species ; external surface ribbed, 
striated, or smooth. 
1 . Dentalium niters. —The Shining Dentalium, pi. XCVIII. 
fig. 62. 
D. nitens. Sowerby, I. p. 159, pi. 70, figs. 1, 2. 
Almost straight, gradually tapering to the smaller end, which 
is somewhat thickened; openiug at the point, circular; aper¬ 
ture expanded ; surface even and shining. 
In the London Clay, Highgate. 
2. Dentalium acuminatum. —The Pointed Dentalium, pi. 
XCVIII. fig. 74. 
D. entalis. Sowerby, I. p. 159, pi. 70, fig. 3. 
Slightly arcuated, nearly smooth, with the lines of growth 
on the surface a little waved; opening of smaller end, smooth; 
the aperture acute in the edge. 
The London Clay, Hordwell Cliff, &c. 
3. Dentalium striatum. —The Striated Dentalium, pi. 
XCVIII. fig. 09. 
D. striatum. Sowerby, I. p. 100, pi. 70, fig. 4. 
Surface with ten or eleven very regular, longitudinal, acute, 
prominent striae, which are most elevated at the smaller end 
of the shell, giving it a triangular appearance ; between each 
of the larger striae are from one to four very minute interven¬ 
ing ones, which are most conspicuous towards the middle of 
the shell, with numerous fine lines of growth ; aperture circular; 
length, about tw T o inches. 
The London Clay, Barton. 
4. Dentalium decussatum. —The Decussated Dentalium, 
pi. XCVIII. fig. 59. 
D. decussatum . Sowerby, I. p. 101, pi. 70, fig. 5. 
Surface with upwards of twenty longitudinal striee, and 
several obscure intervening ones, with numerous distinct 
oblique lines of growth; aperture elliptical; diameter of the 
shell nearly double that of D. striatum. 
Chalk Marl, Newtimber, Sussex; the Gault, Westerliam, 
and llidge, Sussex. 
5. Dentalium ellipticum. —The Elliptical Dentalium, pi. 
XCVIII. fig. 03. 
I), ellipticum. Sowerby, I. p. 101, pi. 70, figs. 0, 7. 
Nearly straight, abruptly tapering, and somewhat compressed; 
surface rather uneven, covered with rough lines of growth; 
aperture circular, with the external edge elliptical; diameter 
of aperture nearly half an inch in some specimens. 
The Gault, Folkestone, and Greensand, Blackdown. 
0 . Dentalium costatum.— The Ribbed Dentalium, pi. 
XCVIII. fig. 73. 
D. costatum. Sowerby, I. p. 102, pi. 70, fig. 8. 
Surface with from twelve to fifteen close set ribs, the fur¬ 
rows being about equal in width ; crossed by obscure lines of 
growth; aperture circular. 
The Red Crag, Holywell, and Coralline Crag, Sutton. 
7. Dentalium planum. —The Plain Dentalium, pi. XCVIII. 
fig. 72. 
D. planum. Sow’erby, I. p. 179, pi. 79, fig. 1. 
Gradually tapering, and gently curving; surface smooth; 
aperture circular, with the lip a little thickened, and sharp at 
the edge ; small end rather acute ; length about an inch. 
The London Clay, Bognor, Reading, &c. 
8. Dentalium cylindricum.— The Cylindrical Dentalium, 
pi. XCVIII. fig. 71. 
D. cylindricum . Sowerby, p. 179, pi. 79, fig. 2. 
Nearly straight, hardly tapering, the smaller end being 
nearly as wide as the other; cylindrical, smooth; aperture 
circular. 
The Greensand, Exmoutli, Devon. 
9. Dentalium incrassatum. —The Thickened Dentalium, 
pi. XCVIII. fig. 70. 
D. incrassatum . Sowerby, I. p. 180, pi. 79, figs. 3, 4. 
Greatly tapered, curved, swelling near the aperture, which 
is circular, with a sharp lip; surface smooth. 
The London Clay, Highgate. 
10. Dentalium medium. —The Middle-sized Dentalium, 
pi. XCVIII. fig. 05. 
D. medium. Sowerby, I. p. 181, pi. 79, fig. 5. 
Gradually tapering, somewhat trumpet-shaped internally; 
aperture circular, wide, lip sharp, and becoming suddenly 
small; external surface covered with transverse striae, or con¬ 
spicuous lines of growth; substance of the shell thin. 
Lower Greensand, Blackdown. 
11. Dentalium anceps. —The Obscure Dentalium, pi. 
XCVIII. fiig. 7. 
D. anceps. Sowerby, Geo. Tr. 2nd Ser. V. p. 130, pi. 8, 
fig. 17. 
Slightly arcuated; longitudinally ribbed for a third of its 
length from the apex; one rib on each side being prominent 
and sharp; the lower portion smooth ; aperture round. 
The London Clay, Hampstead. 
12. Dentalium entale. —The Entalis Dentalium, pi. 
XCVIII. fig. 64. 
D. entale. Deshayes, Mon. pi. 15, fig. 7. 
Slender, smooth, glossy, and somewhat arcuated, tapering to 
a small pervious point, sometimes with a few transverse 
wrinkles. 
