264 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 Crinoideze 
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 Lxcrinus 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 palzozoic 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 Crinoidez, that is those not rooted to the soil by a 
stem, of which the Comatuda may be considered the type, only 
appeared at a later period. They are absent in the palzozoic 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 Astroites. At the same time, and since 
that epoch, the Crinoidez, which we know by the name of stone lilies, 
and which characterise the Aluschelkalk rocks, have been known 
under the name of Encrinus,. from «», stone, and xplvoy, a lily. 
During the eighteenth century the works upon the Crinoideze 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 
