PROTOZOA, CCELENTERA, AND ECHINODERMA 99 



Several years before tlie ' Lightning ' was 

 despatclied on her memorable pioneering voyage, 

 Vaughan Thomson had proved that the common 

 feather star of the shallow waters of the British 

 coasts passes through a stage in its development which 

 resembles the fossil genera of the order in being 

 provided with a stalk for attachment. 



But it was left for the naturalists of the 

 * Porcupine,' the ' Challenger,' the * Talisman,' and 

 other vessels employed in deep-sea researches to prove 

 that adult stalked Crinoids are still living in nearly 

 all parts of the world at the great depths of the sea. 



The genera of stalked Crinoids now living 

 are the remains of a family that at one time had 

 many representatives in all parts of the world. 

 Nearly all the marine deposits of bygone epochs, 

 including even those of such remote periods as the 

 Cambrian and Sub-Silurian, contain the fossilised 

 skeletons of these Crinoids. In some strata they are 

 represented by only a few genera, but in others they 

 are found in such enormous numbers that the sea- 

 beds of those early times must have been literally 

 carpeted with them. 



At the present day the few genera that survive 

 have been driven from the shore waters, and are 



