90 SUPPLEMENT TO THE CRAG MOLLUSCA. 
the one which if we had the evidence of fossil specimens only for a guide I should be 
disposed to regard as most entitled to specific distinction, is that figured by me in Tab. 
XVII, fig. 3 4, under the name of var. punctura ; and to show this better I have given in 
Tab. VII, fig. 24 of this ‘Supplement’ an enlargement of the sculpture on this var. 
punctura. As to the proportional length of the fissure and shape of the shell, I find it to 
vary so irregularly as to be no guide for specific distinction. H. capuliformis, * Phil. Mol. 
Sic.,’ Vol. I, p. 116, Tab. VII, fig. 12, is merely a distortion of one or other of these 
forms, and I have the same among my specimens. 
HMARGINULA CRASSA, J. Sow. Crag Moll., vol. i, p. 165, Tab. XVIII, fig. 2. 
Localities as in ‘ Crag. Moll.’ 
The shell with this name from the Coralline Crag differs materially from that found in 
the Red Crag, being much smaller; it also has rounded and more prominent rays, is 
more conical or elevated, and has comparatively a deeper sinus at the margin, while it 
differs as much from the Red Crag shell of this name as any of the five forms, rosea, 
Jissura, cancellata, elongata, and decussata do from each other, and if they are to remain 
specifically distinct I would call my Coralline Crag shell a separate species also under the 
name /7. crassalta. Specimens of H#. crassa from the Red Crag measure 27 inches in 
length. 
FissurELLA costartA, Basterot. Supplement, Tab. VII, fig. 19. 
TISSURELLA cosTARIA, Bast. Mem. Geol. Bord., p. 71, 1825. 
o neGLECTA, Desh. Exp. Sci. de Morie., p. 134, 1844-8. 
—- MEDITERRANEA, Gray. Apud. Sow. Conch. IIL, fig. 30. 
— Iratica, Hornes. Vien. Foss. p. 641, t. 50, fig. 80. 
Length, 12 inch, breadth 14 inch. 
Locality. Coyralline Crag, Sutton. Red Crag, Waldringfield (A. Bell). 
A fine specimen has been obtained from Sutton by Mr. Bell and put into my hands 
for description with the name of 7. neglecta. 'This name was first given by Deshayes, 
‘Coq. Foss. des Env. de Par.,’ Tome II, p. 20, PI. II, figs. 10—12, but rejected in his 
second work as not belonging to the Paris Basin, and Basterot adopted the above name. 
This shell much resembles /. gre@ca, and its principal difference appears to be that 
the decussating lines, or lines of growth, are stronger and closer in this species, and the 
rays or radiating ridges are more uniform, and not alternate, as in 7. greca; but the 
young of greca is very variable in its markings, and the keyhole opening is broader in 
the very young shell, near the recurved vertex, than it is on the anterior side. 
Tab. 483, figs. 1—3, ‘Min. Conch.,’ belongs, I believe, to & greca, Linn., and not to 
the present species. 
