ASTEROIDEA 139 



1. Asterias Linnaeus. 

 (Syn. Aster acanthi on Miill and Troschel.) 



Rays 5 or 6, rather short, broad, tapering ; disk fairly large. 

 Dorsal skeleton of arms forms an open, irregular network, leaving 

 rather large, naked spaces containing several small papulae. 

 Sj^ines of dorsal side in a more or less regular series along the 

 mid-line of arms and on the marginal plates, otherwise not 

 arranged in distinct longitudinal series. Adambulacral spines 

 alternating one and two, though not quite regularly. Pedicellariae 

 are generally attached to the inner adambulacral spines. Genital 

 openings on the dorsal side. 



Only one species known from British and European seas. 



1. Asterias rubens Linnaeus. Common Crossfish. (Fig. 79.) 



(Syn. Asterias violacea O. Fr. Miiller ; Asteracanthion rubens 

 Miill. and Troschel ; U raster rubens ; U. violacea Forbes ; 

 Asterias Murray i Bell.) 



Dorsal skeleton as a rule faintly developed, the dorsal skin 

 being therefore rather soft. Adambulacral spines in the proximal 

 part of arm fairly regularly alternating one and two. Externally 

 to the adambulacral spines generally 3-4, in young specimens only 

 2, ventro-lateral spines in an oblique series (Fig. 81, 2) ; they are 

 sUghtly larger and more robust than the adambulacral ones. The 

 marginal plates generally each with 2-3 somewhat smaller spines, 

 forming longitudinal series along the sides of the arm. Spines 

 along the mid-line of arm in a more or less distinct series, some- 

 times double ; as a rule they are not much larger than the other 

 spines of the dorsal side. Pedicellariae usually scattered over 

 the whole dorsal side, both sorts intermingled ; as a rule 

 not specialty gathered round the spines. Their number varies 

 exceedingly, from very numerous to very scarce. On the oral 

 side almost exclusively straight pedicellariae, especially attached 

 to the inner furrow spines (Fig. 26, 7). Also on the sides of the 

 adambulacral plates, within the furrow, pedicellariae are often 

 found. R. mostly = ca. 4-5 r., more exceptionally only 3-5 r. or as 

 much as 7 r. Reaches a very considerable size, up to ca. 26 cm. R. 

 (these very large specimens chiefly in deeper water). 



Colour varying from reddish -brown to dark violet ; specimens 

 from deeper water as a rule more light coloured, a pale reddish - 

 yellow. The dark violet specimens look very different from the 



