GEOLOGICAL DISTRIBUTION OF CRINOIDEA. 309 
According to the present state of our knowledge all those 
peculiar types of radiated animals were created, and each 
_ lived through the destined period alloted to its race, and 
died out ere the deposition of the New Red Sandstone ; not 
a single species, not a relic of the innumerable individuals 
that swarmed in the paleeozoic oceans, has been observed in 
any strata above the Permian. 
The Trias, which ranks as the earliest of the secondary 
formations, is characterized by the advent of two typical 
genera ; the true Encrinus or Lily-encrinite, and the Penta- 
crinus ; the former is unknown in any other deposits ; the 
duration of its race was comprised within the Triassic epoch. 
The Pentacrinus, on the other hand, has been perpetuated 
through all the succeeding periods, and one species inhabits 
the present seas ; the sole existing representative of the most 
ancient type of this order. 
In the Oolite, another living form, the Comatula, first 
appears. 
The ocean of the Cretaceous epoch was inhabited by five 
genera of Crinoids, unknown elsewhere ; among them is that 
remarkable genus, the Marsupite. 
The Crinoidea of the Tertiary seas are as few in number 
and variety as those of the present day ; not a vestige of any 
of the ancient tribes has been discovered. M. D’Orbigny’s 
Tab. 12 presents the phenomena thus briefly noticed, in a 
striking point of view. 
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From this review of the fossil Crinoidea and Asteriadee, 
the student will be in some measure prepared for the collecting 
of instructive specimens from the immense accumulation of 
remains imbedded in certain strata of the Oolitic, Liassic, 
Carboniferous and Silurian rocks. 
The British species of fossil Crinoidea amount to more 
than two hundred ; and when the great number of bones 
