65 



P. Caput Medusas. The Column differs in its joints, being thinner, and their 

 having been covered all over with a more conspicuous muscular coat, which 

 shows itself in numerous minute tubercles, the result of its contraction. 



I apprehend that the superior extremity figured in WHITEHURST and PAR- 

 KINSON, as mentioned above, belonged to this species. I also conceive that a 

 specimen in the possession of Mr. G. HAWKER, from the banks of the Severn, 

 but much disfigured by pyrites, appertains to it. 



I If 18 



