82 PETRIFACTIONS AND THEIR TEACHINGS. CHAP. II. 



surface. Now, if we imagine a Starfish placed with its mouth up- 

 wards and the five rays fringed with long articulated tentacula, 

 and fixed by the centre of its dorsal surface upon a' jointed 

 stem, we shall have the essential characters of a Crinoidean ; 

 and the animals of one recent genus of Asteridce are actually 

 in this condition in the earlier stage of their existence : these 

 are the Comatulce, or Feather-stars. 1 



From the importance of the Crinoidese in the economy of 

 the ancient world, the history of this only crinoideal type at 

 present inhabiting the European seas, which once swarmed 

 with these beautiful creatures, presents many points of inte- 

 rest to the naturalist. The receptacle of the soft body of the 

 Comatulce, like that of the crinoideans, consists of a cup- 

 shaped calcareous base, which sends off from its margin five 

 arms, that quickly subdivide, and are beset on each side 

 with rows of articulated pinnae ; on the convexity there are 

 also numerous slender-jointed simple tentacula. The mouth 

 is situated in the centre of the area surrounded by the arms, 

 and is capable of being elongated. In the young state, the 

 Comatulse are attached by a jointed stem to other bodies. 2 

 The stem is composed of about eighteen joints, which are 

 pentangular. After a few weeks the Feather-star becomes 

 detached from its peduncle, and ranges the sea in freedom. 



Four fossil species of Comatula have been discovered in the 

 Solenhofen slate ; and it is not improbable that some of the 

 numerous Crinoideans may be species of this genus in the 

 early stages of development. 



In another group of Asteridse (named Ophiura or Serpent- 

 stars) the rays are long and slender, and without grooves or 

 tentacula, and are distinct from the body. These organs are 

 extremely flexuous, and in some species beset with spines, and 

 enable the animal to seize and entwine round its prey. There 

 are several fossil Ophiura from the lias in this Case. 



Goniaster. These Starfishes are of a pentagonal form, and 

 bordered by marginal plates ; several fossil species occur in 

 the white chalk, and in this collection there are some beautiful 



1 The reader interested in this subject should peruse the elegant and 

 charming volume on British Starfishes and other Echinoderms, by 

 Professor Forbes. 1 vol. 8vo. John Van Voorst. 1841. 



2 See "Medals of Creation," p. 333. 



