SEA-STARS AND SEA-URCHINS. Q9 



into which life and mobility had been infused. The discovery 

 was hailed with joy by naturalists, and the little stranger was 

 named Pentacrinus europczus. Thirteen years later Thompson 

 came to the conclusion that his Pentacrinus was only the 

 larval form of Comatula; and in 1840 Edward Forbes, Robert 

 Ball, and C. Wyville Thomson were dredging in Dublin Bay, 

 when the dredge brought up specimens of the so-called Penta- 

 crinus in a more advanced stage than had been seen hitherto, 

 and behoM, some of these underwent the final change in their 

 early history under their eyes : the Feather-star left its stalk 

 and floated off, a true Comatula. Sir C. Wyviile Thomson has 

 given this interesting account of its progress from the egg 

 condition : 



" The young escapes from the egg a pear-shaped free 

 animalcule, swimming and gyrating rapidly through the water, 

 large end foremost, by four transverse bands of cilia, and by 

 a tail-like tuft of long cilia, which it uses somewhat in the 

 style of a screw propeller. On one side of the body there is 

 a large oval mouth, richly ciliated, and a short curved stomach. 

 After swimming freely in this form for several days, a network 

 of calcareous plates begins to appear, at length making a 

 closed chamber in the wide end of the pear, and extending as 

 a sort of stalk to the narrow end. The stalk now lengthens, 

 and the creature loses its symmetrical form ; it attaches itself 

 to a stone or seaweed, and from the free, wide extremity, 

 there springs a little circlet of branches the arms of the 

 second stage." 



On turning again to the illustration (page 93), it will be seen 

 that the Rosy Feather-star, to give it the full title, is possessed 

 of ten rays, or rather five rays each forking into two, and that 

 these branches are pinnate, or feathered with little appendages 

 which contain the ova. The ordinary organs are all contained 

 in the central body, and do not extend into the rays as in 

 Five-fingers. 



The remaining figure in that plate is the Purple-tipped Sea- 



