86 
Reference and Synonymes. 
G. CumBERLAND, in Transactions of Geological Society, Vot. v. Pu. 111. 
fig. 1. 
Locality. 
At Clevedon, in the Magnesian beds of the Mountain Limestone; at Wood- 
spring, Black Rock (14th bed of Dr. Bricur’s series in Geological Transac- 
tions, Vou. 1v.) near Bristol, in the same formation. 
Observation. 
The Couvumn (fig. 27. and 31.) of this species is of a round form, and its 
joints, particularly near the summit, having been very muscular externally, 
have their margin rounded inwards near the surface of articulation, evidently 
the result of contraction. The alimentary canal is near the pelvis subquin- 
quangularis (fig. 20.) becoming round further from it (fig. 2k.) The centre of 
the columnar joints is depressed and smooth, surrounded by a radiatingly stri- 
ated rim towards the exterior. 
Round Sipe Arms (fig. 25. and 27.) came off irregularly from the column, 
they are of considerable length, and must have possessed an high degree of 
muscularity, demonstrable by their frequently coiling up (fig. 26). and the mar- 
gin of their joints being rounded inwards, as in the column. 
The Pexvis (fig. 2. and 3.) is saucer-shaped, and composed of five plates, 
forming in the centre a subpentangular perforation, the entrance to the alimen- 
tary canal, which was probably once defended by a sphincter. At the inferior 
part, the pelvis is excavated for the firmer adhesion of the columnar joint, with 
which it corresponds in its striated markings. 
The Cosrars. (fig. 4. and 5.) At the summit the plates of the pelvis 
are more or less angularly pointed, where, in the spaces thus formed, the cos- 
tal plates insert. Four of these are subhexagonal (fig. 4.) and one is subhep- 
tagonal (fig. 5.) from having its superior angle truncated. 
The Scapure (fig. 6, to 9. and 14.) which insert between the angular sum- 
