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SERPULA obtusa. 
TAB. DCVIII.—/ig. 8. 
Srec. Cuar. Repent, smooth, obtusely quadran- 
gular, with an obtuse thick keel along the flat 
back; edge of the aperture produced as a short 
cylinder beyond a bilobed thick margin ; base 
expanded. 
Aumost as thick asa goose quill ; when young the aper- 
ture has a tooth at top, and when nearly full grown the 
edge is much thickened by two reflected variciform lobes, 
that meet upon this tooth; when quite perfect, a short cy- 
linder projects beyond these lobes. ‘The surface is re- 
markably smooth, the lines of growth very indistinct ; 
the keel is sometimes wavy and sometimes even. 
A beautiful group of this Serpula upon a portion of an 
Inoceramus, from part of which the figure is copied, is 
in the rich collection of C. B. Rose, Esq., it is from the 
Upper Chalk of Sayham in Norfolk. 
SERPULA fluctuata. 
TAB. DCVIII.—fg. 5. 
Spec. Cuar. Repent, smooth, circular, with five 
regularly waved low keels. 
Tuts very neat little Serpula is at once known by its 
regularly waved wire-like keels; the surface of attach- 
ment is small. 
Found upon various shells in the Upper Chalk at 
Norwich: we have it from the Rev. G. R. Leathes and 
Mr. Barnes. 
