FOSSIL STAR-FISHES AND SEA-URCHINS. 133 



have been so regularly and beautifully jointed, the 

 former even more effectually than a mediaeval mail- 

 clad knight. The two groups so anciently separated 

 are easily recognized. Thus the "five-fingers" and 

 " sun-stars " (Solasters) so abundant on our British 

 coasts have the under surfaces of their arms grooved. 

 In and out of these grooves we perceive rows of 

 small, white, grub-like objects, which slowly wriggle 



Fig. no. — Recent "Five-finger" ^fax-^^ {,U raster rttbcns). 



to and fro if we turn a star-fish on its back, and finally 

 end by bending over and attaching their tips to 

 the ground by means of suckers. Then by a united 

 exertion they pull over the star-fish to its proper 

 position. A young observer has not long to experi- 

 ment on living star-fishes before he finds that these 

 grub-like objects serve all the purposes of feet — that 

 the star-fishes can glide along even perpendicular 



