PHYSIOLOGICAL CONSIDERATIONS. 431 
presents the angular column of the Pentacrinite; 
with this one exception, pentangular columns 
first hegan to abound among the Crino'ideans at 
the commencement of the Lias, and have from 
thence extended onwards into our present seas. 
Their several species and even genera are also 
limited in their extent ; e. g, the great Lily 
Encrinite (E. moniliformis) is peculiar to the 
Muschel Kalk, and the Pear Encrinite to the 
middle region of the Oolitic formation. 
The Physiological history of the family of 
Encrinites is very important; their species were 
numerous among the most ancient orders of cre- 
ated beings, and in this early state their con- 
struction exhibits at least an equal if not a higher 
degree of perfection than is retained in the exist- 
ing Pentacrinites; and although the place, which, 
as Zoophytes, they occupied in the animal king- 
dom, was low, yet they were constructed with a 
perfect adaptation to that low estate, and in this 
primeval perfection they afford another example 
at variance with the doctrine of the progression 
of animal life from simple rudiments through a 
series of gradually improving and more perfect 
forms, to its fullest development in existing spe- 
cies. Thus, a comparison of one of the early 
forms of the Genus Pentacrinite, viz. the Bri- 
arean Pentacrinite of the Lias, (PL 51 and PL 
52, Fig. 2, and PL 53) with the fossil species of 
more recent formations, and with the existing 
