STAR-FISH AND SEA-UPtCIIIXS. 271 



adv^anccs with a leap or bound about the distance 

 of two inches, and as the strokes follow one another 

 rapidly, the Star-lish is able to travel at the rate of 

 six feet per minute. A common Star-lish, on the 

 other hand, with its slow crawling method of 



Fig. 46.— Natunil movements of a Brittle-star when proceeding along a solid 

 horizontal surface. 



progression, can only go two inches per minute. 

 Some of the Comatuhe, in which the muscularity 

 of the rays has proceeded still further, are able 

 actually to swim in the water by the co-ordinated 

 movements of their rays.* 



* In this cas9 the locomotion of a Star-fish comes to be per- 

 formed on the same plan or method as that of a Jelly-fish — the 

 five rays performing, by their co-ordinated action, the same 

 function as a swimming-bell. It is a cnrionsly interesting fact, 

 that although no two plans or mechanisms of locomotion could 

 well bo imagined as more fundamentally distinct than those 

 which are respectively characteristic of these two groups of 



