142 



ECHINODERMS OF THE BRITISH ISLES 



spines) single (Fig. tSl, 1) ; the marginal plates likewise with a 

 single s])ine each, foniiing two regular series along sides of arms. 

 Spines of the dorsal side generally only indistinctly arranged in 



Fig. 80. — Leptasterias Mulleri. Nat. size. 

 (From Dmimarlc's Fauna.) 



longitudinal series, more distinctly in younger specimens. They 

 may be rather distinctly knob-shaped, especially those along the 

 mid-dorsal line. The pediceUarise mainly collected around the 



spines ; the straight ones 

 generally only at the ambu- 

 lacral furrows, R = ca. 4-7 r. 

 Reaches scarcely a larger size 

 than ca. 100 mm. R. Colour 

 in life a faint red or violet on 

 the disk and proximal part 

 of arms ; whitish towards the 

 end of arms. 



The breeding season is in 

 early spring (March - April). 

 It protects its brood ; the 

 eggs are kept around the 

 mouth in the space produced 

 by the mother by putting its 

 arms together and raising its 

 back. The embryos develop here, without any free-swimming 

 larval stage ; the young ones do not leave their mother until 

 the three first pairs of tube -feet have appeared. During the 

 whole time required for development the mother does not take 



Fig. 81. — ^Part of right side of ambu- 

 lacral furrow of Leptasterias Mulleri 

 (1) and Asterias rubens (2). x 8. 

 (From Danmark's Fauna.) 



ad, Adainbulacral (furrow) spines; g, Pores 

 of papulie ; p. Pedicellarise ; vl, Ventrolateral 

 spines. 



