136 ECHINODERMS OF THE BRITISH ISLES 



1. Stichastrella rosea (0. Fr. Muller). (Fig. 77.) 



(Syn. Asierias, Asteracanthion, Stichaster roseus (O. F. Miill.) ; 

 Cribella rosea Forbes ; Stichaster arcticus Dan. and Kor.) 



Rays 5, round, gently tapering. Adambulacral spines 

 forming 2-3 close series along each side of the ambulacral furrow. 

 Outside these some shorter spines, likewise arranged in longi- 

 tudinal series ; they form the transition to the grains of the 

 dorsal side. Madreporite large and distinct, surrounded by a 

 circle of grains. The straight pedicellariae on the sides of the 

 ambulacral furrows. The crossed pedicellariae on the dorsal side, 

 especially on the sides of arms. R=ca. 7 r. Reaches a size of 

 ca. 15 cm. R. Colour in life orange-reddish or more yellowish. 



Development only partially known, but, in any case, it has a 



Fig. 77. — Stichastrella rosea. Dorsal side. Somewhat reduced size. 

 (From Danmark's Fauna.) 



true pelagic larva, probably with a Brachiolaria stage. The 

 breeding season is August-September. About its food nothing is 

 known, but it appears that ciliary currents do not have the role 

 of carrying food to the mouth. It appears to prefer a sandy 

 bottom. 



In British seas this species occurs all around the coasts, 

 excepting the Channel coasts. It is othermse known only from 

 the Bay of Biscay to Lofoten on the Norwegian coast. It is a 

 shallow- water species occurring from ca. 4 m. down to ca. 430 m. 



In deeper water, ca. 400-1300 m., off S.W. Ireland, a form of 

 Stichastrella has been found (" Helga ") which differs from the 

 typical St. rosea in having stouter and shorter arms — R =ca. 5-8 r. 

 — and in the arrangement of the dorsal skeletal plates being more 

 regular than is usuall}^ the case in St. rosea. As there seem, 

 however, to be no other constant differences it can scarcely 

 represent another species, and is designated as var. ambigua 

 Farran. 



