49 
SERPULA ? extensa. 
TAB. DCXXXIV.— /g. I. 
Spec. Char. Nearly straight, faintly corrugated ; 
shell thick, the greater portion of it free; 
aperture round. 
Syn. Serpula extensa, Brand. Foss. Hants. 12. 
pi. 1./ \2. Morris, Catal. 66. 
The tube diminishes slowly and regularly until near the 
apex, when it contracts rather suddenly. The surface is 
marked with broad, annular, slightly raised ridges, which 
are numerous and nearly equal; otherwise the shell is 
smooth; it is composed of several laminae, which together 
give a considerable thickness. 
Great numbers of solitary fragments of this shell are 
found in Barton Cliff, but any mark of attachment is rarely 
met with. It has long been doubted whether these frag- 
ments may not be portions of the tubes of Teredo antenautce ; 
but the shell of them is thicker than Teredo generally has 
it, and I am not aware that thev are ever found at Barton 
with remains of wood around them. Clusters of very 
similar tubes occur at Bognor imbedded in fossil wood ; 
sometimes they are even more tortuose, and therefore 
more like the usual form of Serpulee ; in these however the 
shell is still thin and fragile. The specimens figured are 
in the cabinet of Mr. Edwards. 
Fig. 1. a. is a magnified representation of a portion 
showing the surface of attachment. 
