106 ECHINODERMATA. 



5. ASTERIAS ENDECA Nine-rayed Star-fish. PLATES XIX. figs. 7, 

 8, 9 XXII. XXIII. 



The species described in the preceding paragraphs are all provided 

 with five rays, which, as before said, are commonly uniform, without 

 deficiency or redundance. Those of the Star-fish described in the pre- 

 sent paragraph are not alike uniform in number, being eight in the speci- 

 men, Plate XIX. fig. 7 ; nine, the full complement, in fig. 9 ; and nine 

 in the specimens Plates XXII. and XXIII. The animal has also occurred 

 with ten. This is one of the larger and more beautiful of the Star-fish 

 inhabiting the Scotish seas, expanding eight inches between the opposite 

 tips of the rays. The usual complement of these, I say, is nine. They 

 diminish regularly from the root to the extremity. Two rows of suckers 

 occupy their under surface. 



The texture of -the skin is rough, and its formation and appearance 

 are very peculiar. Not less varied is the colour, specimens being seen 

 from pale yellow, or brilliant orange, to fine purple. Some of the former 

 are speckled white, or a white line runs down the middle of the surface 

 of the rays. There is no uniformity of colour whatever to guide the 

 observer. 



But the structure of the surface, whereby, perhaps, the colour is 

 entirely modified, is neither explicable nor intelligible. It is of remark- 

 able complexity. 



The skin or integument being porous, and the animal having the 

 faculty of elevating some singular parts of its organization above the sur- 

 face, through the pores, as well as of withdrawing them, the appearance 

 must necessarily depend on the mode wherein this faculty is exercised. 

 I see no other means of accounting for its changeable aspect. 



The specimen Plate XXIII. fig. 1, expanded seven inches, and was 

 of a fine delicate purple above, the under surface of a dingy straw yel- 

 low. A number of projecting minute white tufts, interspersed with short 

 cylindrical tubes, studded the upper surface, the skin being thin and 

 flexible. The colour was no less modified by the proportional projection 

 of the tufts. When they were depressed it was much darker, when they 

 were elevated much lighter. A portion enlarged is represented fig. 2. 



