260 COMPAKATIVE ZOOLOOY. 



water is instant death to them. They have the power of 

 reproducing lost parts to a high degree. They are very 

 voracious, and are the worst enemies of the Oyster. 



Fig. 212. — Under •surface of Star-fisb {Goniastei- reticv-tatua), showing nmbulaeral 

 grooves and protruded suckers. 



About one hundred and fifty species are known. These 

 may be divided into two groups: (1) species having four 

 rows of feet, represented by the common five -fingered 

 Asterias; or having two rows of feet, as the many.rayed 

 Solaster, or "Sun -star," and the pentagonal Ooniaster ; 

 (2) species having long, slender arms, which are not pro- 

 longations of the body, and are not provided with suck- 

 ers, as the Ophiura, or "Brittle-star," and Astrophyton, or 

 " Basket-fish." The last are of inferior rank, and resemble 



