120 ECHIN0DERM8 OF THE BRITISH ISLES 



the normal way ; sometimes also both eggs and embryos are 

 found free, pelagic. There is no Bipinnaria stage. The number 

 of eggs is ca. 500. The breeding season is February-April 

 (May). 



It is not known upon what this sea-star normally feeds. It is 

 generally found empty. It has been observed in the mounted 

 position over a Mytilus, and thus may be supposed at least 

 occasionally to feed on mussels. A semiparasitic copepod, 

 Astrochceres Lilljeborgi Boeck, is usually found on its skin, 

 moving swiftly among the spines, but holding very tightly with 

 its feet ; it has sucking mouth parts, and doubtless sucks its 

 nourishment from the sea-star, like a sort of louse. Also Dendro- 

 gaster, a very much transformed and reduced cirripede, is known 

 to live entoparasitic in this species. 



In British seas this species is rather common all round the coasts, 

 excepting perhaps on the Channel coasts. It is found in all depths 

 from between tide-marks down to ca. 1000 metres or probably more. 

 It is otherwise distributed southwards to the Bay of Biscay and 

 the Azores ; further in the Scandinavian seas, from the Baltic to 

 the Arctic region, Iceland, Greenland, and the North American 

 coast down to Cape Hatteras ; also in the North Pacific down to 

 Washington and the Kuriles. It is stated to occur down to a 

 depth of ca. 2450 metres. 



2. Henricia ahyssicola (Norman). (Fig. 71.) 



(Syn. Cribrella sanguinolenta var. abyssicola Norman ; 

 Cribrella oculata, var. cylindrella Sladen.) 



Rays very long and slender, nearly cylindrical. Spines on 

 the adambulacral plates more or less distinctly arranged in 

 three transverse series ; those on the outer surface of the adam- 

 bulacral plates much smaller than the furrow spines, no gradual 

 passage existing from the longer furrow spines to the short outer 

 spines. One, or in the proximal part of the rays two, longi- 

 tudinal series of larger plates parallel to the adambulacral series. 

 Spines of the dorsal side very fine, in fairly dense groups. R = ca. 

 6 r. Colour in life creamy-white to saffron-yellow. Appears to 

 reach only a small size, ca. 5 cm. R. 



Biology unknown. 



In British seas this species has been found off S.W. 

 Ireland (" Helga ") and in the warm area of the Faroe Channel 



