POTERIOCRINID/E. — POTERIOCRINUS. 73 



inquiring as to the description of enemies thej^ had to contend with, and by what 

 dangers they were surrounded in the tranquil depths of the carboniferous seas, 

 where they might be supposed to have lived in peaceful security for the full term 

 of life assigned them by nature. Such however was not the case, for certain predaceous 

 fish, if we can judge by the coprolitic matter so abundant in some beds of mountain, 

 limestone, devoured them and other genera with the same gusto as a hungry cod of our 

 own seas does their living analogues, the starfish and sea-urchins, and with the same 

 selfish disregard to their symmetrical forms and ornamented exteriors. 



As the boundless extent and fathomless depths of the ocean are, and always have 

 been, since the first creation of carnivorous beings, a continual scene of rapine, tiie Lily- 

 stars in their turn captured and fed on such creatures as they were able to master, among 

 which, certain moUusca appear to have been the favourite aliment of the Poteriocrini. 

 Of these we consider the spined Producta and its ova to have been the chief support, 

 for wherever the remains of the Poteriocrinus occur, there the Productas are found asso- 

 ciated with them, in the same manner as the recent sea urchins and starfishes are observed 

 on the Mactra and oyster beds. 



The Poteriocrinus was well able with its long and powerful arms to seize on any 

 luckless mollusk that crawled within its circumscribed sphere of action, tethered as it was 

 to the bed of the ocean; and if it also possessed the power of injecting any acrid fluid 

 into the gaping shell, as the starfishes are supposed by some to be capable of secreting, 

 then the destruction of its prey would be certain. 



To get at the mollusk the Poteriocrinus must have arched round its column like a 

 swan's neck, until the long oral tube and rays reached the bottom where the shell fish 

 rested in fancied security, when folding it in its pliant but powerful rays, the captive was 

 borne from its rocky bed by the crinoid resuming its upright position, where it could 

 regale on the imprisoned mollusk at leisure: or it might have finished its meal whilst in 

 its curved state. 



In these predatory explorations an insidious side arm might have been occasionally either 

 accidentally or otherwise introduced into the shell of the producta and detained by 

 its closing valves as security against further aggression, when in its efforts to regain its 

 freedom the struggling crinoid may have torn its entrapped member from the column, 

 leaving an indelible mark of the wound as evidence of its rapacity, or prying propensities. 

 Or the smaller rapacious fish may have seized on and torn away the tempting looking 

 bait. 



The latter suggestion is the least probable of the two, as it is known that the side arms 

 of recent crinoids can resist a considerable strain, or cling with great tenacity to any 

 object they infold in their grasp. 



Though the Poteriocrinus is chiefly met with in company with the Productas, other 



