304 ECHINODERMS OF THE BRITISH ISLES 



N. American east coast {Ecldnus WalUsi A. Agass.), is uncertain. 

 Bathymetrical distribution ca. 50-2000 m. 



0. Echinus Alexandri Danielssen and Koren. (Figs. 172, 173.) 



Test flattened on the upper side. Primary tubercles forming 

 very distinct regular series, the secondaries, which are not very 

 numerous, being much smaller than the primaries. The primary 

 spines sometimes very long and rather stout, raised upwards. 

 Every ambulacral plate with a primary tubercle, the two series 

 being very regular, equal sized. No spines on the buccal plates. 



Fig. 172. — Echinus Alexandri ; side view. Somewhat reduced. 

 (After Koehler, Echinodermes du " Caudan ".) 



Globif erous pedicellariae usually with 3-4 lateral teeth on each side 

 of blade. Tridentate pedicellariae with very broad, leaf-shaped 

 valves (Fig. 167, 1) ; they may be rather large, up to 2-5 mm. 

 length of head. Colour in life light pink (fading in alcohol) ; the 

 naked test white. Reaches a size of ca. 70 mm. in horizontal 

 diameter. 



Biology and development unknown. 



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

 (50° 25' N., ir 44' W., 1797 m., " Michael Sars "). No doubt 

 it will prove to have a wider distribution off the west coast of 

 Ireland. It is elsewhere known from S. of Iceland to the Bay of 



