STAR-FISHES 463 



that of the gastropod the star-fish now lowers its sac-like stomach, which 

 is turned inside out through the mouth, the food being digested outside 

 of the body. Small molluscs are also taken into the stomach whole, the 

 empty shells being rejected after the completion of the meal. A branch 

 or cacal pouch extends from the stomach into each arm, where it again 

 divides into two branches. The anus lies on the centre of the upper 

 surface. 



H. Organs of Sense. 



The suctorial feet, or pedicels, form very sensitive tactile organs, while 

 at the tips of the arms are found small red spots which naturalists 

 regard as organs of sight. 



I. Reproduction. 



Eeproduction is effected by means of eggs. The larvse to which they 

 give origin pass through a very complicated metamorphosis before they 

 assume the parent shape. 



Other Echinoderms. 



CLASS II. : THE BRITTLE STARS AND SAND STARS 

 (OPHIUROIDEA). 



Externally these bear a close resemblance to the star-fishes. Their 

 arms, however, are sharply separated from the disc, and are long, thin, 

 and of snake-like flexibility (hence name; Ophiura = snake-tail). In 

 some species, hence known as "Medusa-heads" (explain the name), 

 they are branched like trees, or arborescent. 



CLASS III.: THE FEATHER STARS OR SEA-LILIES 

 (CRINOIDEA). 



This is a group of echinoderms which is almost extinct (fossil crinoids) ; 

 only scanty remnants have survived to our time, and most of these 

 live in the deepest, most inaccessible abysses of the ocean. Their 

 small cup-shaped body is supported upon a fixed jointed stalk, and is 

 furnished with a crown of much-branched arms (feather stars), so that 

 these delicate, often richly-coloured creatures are more like a flower 

 than an animal (sea-lily). Along the coast are found species — e.g., the 

 Mediterranean Feather Star (Antedon rosacea), which is of the most 

 beautiful colours — which are sessile only during the early stages of their 

 life, but later on sever their connection with the stalk, and by means of 



