107 



(as far, he says, as I have been able to ascertain) and make 

 room for the different species o? pejitacrinites, which may be 

 traced through the beds of the Has, ooHte, and chalk : and 

 of which one species, the pentacrinus caput medusce, has 

 continued from the formation of the lias to our times, and is 

 now met with, though very rarely, in a recent state." 



The apiocrinites rotundus is only found adhering to a 

 bed of the oolite formation, and the apiocrinites ellipticus 

 in chalk. 



The radiated echinodermata. — The first section of animals 

 under this division contains the stelleridce, distinguished by 

 their possessing a coriaceous skin, not irritable, but move- 

 able in several points ; the body depressed, wider than long, 

 with radiating marginal angles or lobes, more or less nu- 

 merous and moveable. They are furnished with spines, 

 which are fixed on moveable tubercles ; and in some of the 

 genera of this section there exists on the back, opposite to 

 the mouth, a short tubercle, or a reticulated disk ; but it has 

 not yet been ascertained what office this part performs. 

 The mouth of these animals is surrounded by five little 

 ossicles or granular substances. 



This family is divided, by Lamarck, into four genera: — 

 1. Coynatida ; 2. Euriale ; 3. Ophiura ; 4. Asteria. 



Comatula. — An orbicular, depressed, radiated body, 

 having two sorts of rays, dorsal and marginal, all supplied 

 with calcareous joints. The dorsal rays are very simple, 

 small, cirrous, and filiform, disposed like a coronet on the 

 back of the disk. The marginal rays are always pinnated, 

 and much larger than the simple rays ; their inferior pinnulae 

 are elongated, flattened beneath, and surround the ventral 

 surface. The mouth is beneath, central, isolated, mem- 

 branous, tubular, and projecting. 



The dorsal rays of this animal, by which it clings to 

 other substances whilst seeking for or retaining its prey by 

 its pinnated rays, with its membranous projecting mouth in 



