298 



ECHINODERMS OF THE BRITISH ISLES 



The ])uccal plates carry some small club-shaped spines among 

 the numerous, mostly ophicephalous pedicellariae. Globiferous 

 peclicellariae fairly large, usually with only one lateral tooth on 

 each side, below the end tooth. Tridentate pedicellariae with long, 

 slender valves. Colour of test an intense red, on which the white 

 tubercles are very conspicuous ; more rarely it is pale purplish 

 or pale green. Spines reddish, usually with violet point. Grows 

 to a very considerable size, the largest recorded being 176 mm, 

 horizontal diameter, and is thus one of the largest Echinoids. 



The V diTiety fuscus Mrtsn. (Syn. var. depressus Siissbach and 

 Breckner) differs from the typical form by being rather 



Fig. 168. — Echinus esculentus; naked test, in side view. Slightly reduced. 

 (After Koehler ; from Datimark's Fauna.) 



depressed and by its spines being uniformly reddish-brown 

 and somewhat longer than in the typical form. It is fairly 

 common in the North Sea. 



Hybrids between Ech. esculentus and acutus are not rare, 

 where the two species occur together. Also with Psammechinus 

 miliaris it may form hybrids. Anomalies in the test are not very 

 rare. 



The breeding season is in the early summer months. The 

 larva ^ has in the first stage elongate body - rods with the 



^ Echinopluteus Theelii Mrtsn. (Echinodermenlarven d. Plankton Exped., 

 p. 97) is the larva of Echinus esculentus ; there is no reason for maintaining 

 this name. 



