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. 

 XVIII, fig. 3 b, 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. E. 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. 



Emarginula crassa, J. Soio. 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 E. crassalta. Specimens of E. crassa from the Red Crag measure 2|- inches in 

 length. 



Fissurella costarta, Basterot. Supplement, Tab. VII, fig. 19. 



Tissurella costaria, Bast. Mem. Geo]. Bord., p. 71, 1825. 



— neglecta, Desk. Exp. Sci. de Morie., p. 134, 1644-8. 



— mediterranea, Gray. Apud. Sow. Conch. 111., fig. 30. 



— Italica, Homes. Vien. Foss. p. 641, t. 50, fig. 80. 



Length, If inch, breadth 1^ inch. 



Locality. Coralline 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 F. neglecta. This name was first given by Deshayes, 

 'Coq. Eoss. 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 F. graca, 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 F. graca ; but the 

 young of grceca 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 F. graca, Linn., and not to 

 the present species. 



