Or 
D. Gavus. © Mont. p. 496 ¢t.14. f.7.—Turt. D. p. 
40.—Lin. T. 8. p. 238.—D. p. 1067.—An D. Coarc- 
ratuM. Desh in Z. I. 4. p. 193.—Subpellucid, sub- 
arcuated, tapering to a small point, pervious, contracting 
a little towards the larger end, white, glossy, perfectly 
smooth. %. 0,0622. British Channel, not rare. 
D. Tracuea. Mont. p. 427. ¢. 14, f. 10.—Turt. 
D. p. 40.—Lin. T. 8. p. 239.—D. p. 1068.—OrtTHO- 
cERA.T. f. p. 237.—Subcylindric, arcuated, ferrugin- 
ous brown becoming pale towards the smaller end, which 
is closed, truncated and furnished with a small round 
protuberance; marked with regular transverse strie, or 
annulations, aperture round, the margin not contracted. 
+. 0,125 Milton in: Devonshire, rare, in sand. 
TripeE.—AM PHITRITEANZ. 
GENus.—PECTINARIA. 
Tube free, solitary, regular, conical, subcylindraceous, 
open at both extremities, membronaceous or papyra- 
ceous, covered externally with grains of sand or 
minute stones. 
P. Beteica. Lam. I1.—Sapetua. B. Gmel 3749.— 
S. GranuratTa ? Lin. 1268.—Mont. p. 544.— 
S. Tusirormis. Pen 4. t. 92. f. 163.—Don. t. 133. 
Simple, straight, gradually tapering, the grains of sand 
