300 



echinodp:rms of the British isles 



Ech. esculentus. Colour of test white, or with a slight greenish 

 tint ; spines white. Largest size recorded is 57 mm. horizontal 

 diameter. 



Biology and development nnknown. 



Fig. 169. — Echinus tenuispinus, side view. Nat. size. 



This species, which is known only from the British seas, 

 was first found by Canon Norman 25-30 miles north of Unst, in 

 ca. 200 m. (hard bottom) ; more recently some specimens w^ere 

 taken by the " Helga " on the " Porcupine " Bank and a few 

 other places off the Irish w^est coast, in ca. 130-200 m. 



3. Echinus acutus Lamarck. (Fig. 170.) 



(Syn. Echinus Flemingii Forbes ; Ech. depressus G. O. Sars ; Ech. 

 rarispinus G. 0. Sars. ; Ech. cantaber Lambert and Thiery.) 



Test more or less high, usually subconical, not globular as in 

 Ech. esculentus. Spines rather scarce on the upper side, the 

 primaries conspicuously longer and more robust than the 

 secondaries. Primary tubercles forming conspicuous longitudinal 

 series. Only every second or third ambulacral plate carries a 

 primary tubercle. Buccal plates carry only pedicellariae, no spines. 

 Globiferous pedicellariae usually with only one lateral tooth on 

 each side ; the tridentate pedicellariae with long, slender valves, 

 up to 2-5 mm. long (Figs. 143, 5 ; 144, 2). Colour usually whitish, 

 with a red-brown stripe along each series of plates ; these stripes 

 may be of varying breadth and the general colour in accordance 

 herewith becomes now more whitish, now more reddish -brown. 

 Along the edges of the plates are often seen alternating, parallel 



