88 



SATIKDAV I,K( '1 IJJKS. 



but still .showing the general character of the animal with 

 its five fingers or rays, each having, in a median groove 

 beneath, a number of fleshy, disc-tipped tubes, or ambulacrse, 

 ^vhich perform the function of feet, and with its central 

 mouth, a mere circular opening. The common star-fish of 

 the Atlantic coast {listerias vulgaris Htimpson,'^ fig. 3) is the 



Si 







Fir 



Asfcrias 77i/<''i7r/s 



After A. Airassiz.'! 



most destructive to the oyster, and may be taken as a type of 

 the radiate animals. The sexes are separate, and the ova are 

 fertilized in the water just as are those of the oyster. The 

 analog}^ goes yet further, for the young starfish bears no 

 resemblance to its parent, and swims about by means of ro- 

 tating cilia. At first it is a mere spherical mass, and then be- 

 comes bilateral. This first stage is known as the Bvpinnaria 

 stage, (Fig. 4, A, B, C,) and as it grows older a series of arms 

 develop until Ave have what is know^n as the Brachiolaria 

 stage, (Fig. 4 D,) a name given to it when its real character was 

 unknown, a bit of zoological ignorance which, upon com- 

 paring these figures with the adult, you will agree with me 

 was quite excusable. Those who are curious to learn more 



Asteracd7ithion pallidiis A. Agassiz. 



