204 
SERPULA articulata. 
TAB. DXCIX.—fig. 4. 
Spec. Cuar. Externally square, furnished with 
rings, composed of four oval tubercles each, 
placed at remote irregular distances ; angles 
rounded ; aperture round. 
Diameter about two lines; there is no flat space be- 
tween the ribs of which the angles are formed; these 
ribs are thickened into four oval tubercles each time the 
orbicular sharp-edged aperture is completed. 
Found in coarse sandstone of the Upper Greensand 
near Folkstone. 
a 
SERPULA vertebralis. 
TAB. DXCIX.—fig. 5. 
Spec. Cuar. Tube externally square, its angles 
set with longitudinal, blunt tubercles disposed 
in rings placed at short regular distances. 
Somewnart smaller than the last, its tubercles are more 
regularly arranged and more numerous, four in each 
ring. 
Found in the clay of the Castle Hill, Bedford. 
