COMMON BRITTLE-STAR. 61 



OpJdura rosula, Fleming, Brit. Anim. p. 489. Johnston, Mag. Nat. Hist. 



IX. p. 231, f. 26. 

 OpUura spinulosa, Risso, Hist. Nat. cTEur. Merid. p. 272, No. 12, pi. vi. f. 30. 

 Ophiura/ragilis, Blainville, Man. d'Actin. p. 244. 

 Ophiocoma rosula, Forbes, Wern. Mem. VIII. p. 127. 

 Stella echinata, Rondelet, Liber do Insect, p. 123. 



Of all our native Brittle-stars this is the most common 

 and the most variable. It is also one of the handsomest, 

 presenting- every variety of variegation, and the most 

 splendid displays of vivid hues arranged in beautiful pat- 

 terns. Not often do we find two specimens coloured alike. 

 It varies also in the length of the ray-spines, the spinous- 

 ness of the disk, and the relative proportions of rays and 

 disk ; and in some places it grows to a much greater size 

 than in others. It is the most brittle of all Brittle-stars, 

 separating itself into pieces with wonderful quickness and 

 ease. Touch it, and it flings away an arm ; hold it, and 

 in a moment not an arm remains attached to the body. 



The body is round and convex, but when in egg some- 

 times bulges into a pentangular form. It is usually thickly 

 covered with long spines, the only parts of the surface free 

 from them being the large triangular plates opposite the 

 origins of the rays, which are separated from each other 

 by rows of spines, the spaces between the two, which com- 

 pose each pair, being very narrow. There is a variety, 

 however, which has the disk very rough, but not covered 

 with long spines. Beneath, the rays are separated at their 

 origins by small, oblong, pentangular plates. The rays 

 are covered above with small, triangular, carinate, obtusely 

 pointed scales, which lap over one another, like tiles on the 

 roof of a house. Beneath, they are clothed with trans- 

 versely oblong plates. The lateral ridges are broad, and 

 each bears five very long, tapering, rough spines, which 

 are sometimes nearly three times as long as the breadth 



