204 THE OCEAN WORLD. 



diminished as the globe became older or modified in its conditions, 

 so that at the present time only a few types remain in our seas 

 such as the genera Comatula, Pentacrinus, the Medusa's-head of the 

 Antilles, Holopus, and Rhizocrinus of the deep sea all of them 

 probably destined soon to disappear, carrying with them the last 

 reminiscence of the zoological races of the Echinoderms of the 

 ancient world ; and here lies the real interest which the Crinoideae 

 presents to the thinking man. The Encrinites most common in the 

 fossil state are Pentacrinus fasciculosus, belonging to the lias ; 

 Apiocrinus rotundus, which is found in the oolite or Jurassic rocks ; 

 and Encrinus liliformis, which appertains to the triassic period. 

 These three fixed Crinoids seem to have existed in great numbers 

 during an early age of the world namely, the Silurian period. They 

 attained their maximum of development during the Devonian age, 

 after which they begin to decrease. According to M. d'Orbigny, 

 there are thirty-nine genera found in the palaeozoic rocks, two in 

 the triassic, seven in the Jurassic, five in the cretaceous, and only 

 one in the tertiary strata. Of all these genera but two or three are 

 found in the modern epoch to represent the varied forms of these 

 the first inhabitants of the seas. 



The free Crinoideae, that is those not rooted to the soil by a 

 stem, of which the Comatula may be considered the type, only 

 appeared at a later period. They are absent in the palaeozoic and 

 triassic rocks, but appear to have attained their maximum of develop- 

 ment in the Jurassic period. 



The numerous fossilised remains of these curious creatures which 

 abound in different rocks, attracted the attention of learned men at 

 an early period. The Encrinites were among the earliest objects of 

 scientific description. As early as the sixteenth century the cele- 

 brated mineralogist, George Agricola, mentions them under the names 

 of Entrochites, Trochites, and Astro'ites. At the same time, and since 

 that epoch, the Crinoideae, which we know by the name of stone lilies, 

 and which characterise the Muschelkalk rocks, have been known 

 under the name of Encrinus, from ei/, stone, and Kpivov, a lily. 



During the eighteenth century the works upon the Crinoideae were 

 very numerous, though not very correct. They sometimes reported 

 these organic remains to be vegetable ; sometimes they were beings 

 allied to the star-fishes ; at others they were the vertebral column of 

 fishes. Towards the year 1761, however, Guettard, one of the most 

 learned naturalists of his time, understood the real nature of these 

 productions. He had occasion to examine a recent Encrinus sent 

 from. Martinique under the name of Sea-Palm, which was in reality 



