86 



Reference and Synonymes. 



G. CUMBERLAND, in Transactions of Geological Society, VOL. v. PL. HI. 

 fig. 1. 



* ' , 



Locality. 



At Clevedon, in the Magnesian beds of the Mountain Limestone ; at Wood- 

 spring, Black Rock (14th bed of Dr. BRIOHT'S series in Geological Transac- 

 tions, Vot. iv.) near Bristol, in the same formation. 



Observation. 



The COLUMN (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. 21.) The centre of 

 the columnar joints is depressed and smooth, surrounded by a radiatingly stri- 

 ated rim towards the exterior. 



Round SIDE 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 PELVIS (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 COSTALS. (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- 

 iagonal (fig. 5.) from having its superior angle truncated. 



The SCAPULAE (fig. 6. to 9. and 14.) which insert between the angular sum- 



