HOMOLOGIES. 219 
see at once how striking is the resemblance to a 
flower ; turn it downwards, an attitude which is 
natural to these Crinoids, and the likeness to a 
drooping lily is still more remarkable. The oral 
region, with the radiating ambulacra, is now lim- 
ited to the small flat area opposite the juncture 
of the stem with the calyx; and whether it 
stretches out to form long arms, or is more com- 
pact, so as to close the calyx like a cup, it seems 
in either case to form a flower-like crown, bud- 
like in Eucrinus and other genera, and more like 
an open flower in Platycrinus and the like. In 
these types of Echinoderms the interambulacral 
plates are absent; there are no rows of plates of 
a different kind alternating with the ambulacral 
ones, as in the Sea-Urchins and Star-Fishes, but 
the ab-oral region closes immediately upon the 
ambulacra. 
It seems a contradiction to say, that, though 
these Crinoids were the only representatives of 
their Class in the early geological ages, while it 
includes five Orders at the present time, Echino- 
derms were as numerous and various then as 
now. But, paradoxical as it may seem, this is 
nevertheless true, not only for this Class, but for 
many others in the Animal Kingdom. The same 
numerical proportions, the same richness and 
vividness of conception, were manifested in the 
early creation as now; and though many of the 
