172 THE SUN STAR. 



become tense ; and when it desires to withdraw them, a 

 contraction of its muscles drives back the fluid into the 

 concealed vesicle. By this alternate action all the neces- 

 sary motions are obtained. The skeleton of a Star-fish, 

 or that part which remains when all the soft flesh has 

 been removed, is a wonderfully beautiful structure, con- 

 sisting of hundreds of nicely-fitted calcareous pieces 

 arranged in a regular pattern, perfectly symmetrical in 

 all its parts. We cannot undertake to write a description 

 of such a skeleton, which resembles a piece of crochet- 

 work ; but one may easily be procured by any person 

 who will take the trouble to pick up a Star-fish on the 

 shore, and place it for some days in an ant-hill. These 

 nimble anatomists will soon remove all the soft parts, 

 and polish the bones with the greatest care, without 

 injuring or displacing the minutest portion of the shell. 

 An interesting series of specimens might be obtained 

 by preparing such skeletons of all our native kinds. 



The British species of true Star-fishes are fourteen, 

 which are considerably more varied in character than 

 the OPHIUKID/E, or Brittle Stars. In the latter group 

 we have but two generic types ; but in the former there 

 are no less than eight, distinguished from each other 

 by characters taken from the outline of the body, the 

 number of rows of sucking-feet, and the arrangement 

 of the spines covering the surface and bordering the 

 avenues.* These differences are readily seen, and the 

 groups indicated by them appear naturally associated. 

 One of the most beautiful of the commoner kinds is the 

 Sun Star (Solaster papposct), whose disc is surrounded 

 * Forbes's " Star-fishes," p. 75, &c. 



