110 SOLASTERIvE. 



The Solasters are suns in the system of sea-stars. Their 

 many rays and brilliant hues give them a distinguished 

 place among the marine constellations. Two species in- 

 habit the seas of Britain. The genus extends its range 

 far to the south. The Solaster helianthoides, a species 

 nearly allied to our common Solaster papposa, but having 

 many more arms, is found on the western shores of South 

 America. They differ from the Urasters, with which 

 Professor Agassiz proposed to unite them, not only in 

 form and arrangement of spines, but also in having only 

 two ranges of suckers in each avenue, whereas the Cross- 

 fishes have no less than four. 



The Purple Sun-star has from nine to eleven rays, 

 which are rounded and shorter than the breadth of the 

 convex disk. The disk and upper surfaces of the rays are 

 purple ; the under surface and sides of the arms cream 

 colour. Both arms and disk are thickly covered with 

 oblong tubercles, which are scattered on almost all the 

 purple parts, but arranged in irregular rows on the cream- 

 coloured portions. Each of these tubercles is crowned by 

 a circle of strong rough spines, which generally surround a 

 central one, similar in appearance to the others. Beneath, 

 the avenues are narrow. Three sets of spines border them. 

 That immediately bordering each avenue-margin, consists 

 of transverse comb-like rows of from five to ten spines 

 webbed together towards the base. Next to these we have 

 transverse ridges, narrow and compressed, each bearing a 

 double row of shorter spines. Beyond this is a row of 

 tufted spines similar to those upon the upper surface, but 

 thicker. The madreporiform tubercle is sublateral, cir- 

 cular, and finely striate with radiating strife. There is a 

 curious aperture with a spinous border seen in the centre 

 of the back of this and several other Starfishes, the nature 



