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 Encrinus and other genera, and more like 

 an open flower in Platycrinus and the like. In 

 these types of Echiiioderrns the interarnbulacral 

 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, Echiiio- 

 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 



