ECHINOIDEA 303 



Ech. acutus. Colour of test brownish, usually with conspicuous 

 alternating lines of white and brownish along the edge of the 

 plates. Primary spines greenish. Grows to a considerable size 

 like the preceding species, perhaps still larger. 



Development unknown. Appears to prefer a rocky 

 bottom. 



In British seas this species appears to be rather rare, but as 

 it has formerly generally been confounded with Ech. acutus it is 

 quite possible that it is not quite so rare as would appear from 

 literature. It has been recorded from off North Rona ("' Knight 

 Errant ", Agassiz) and from Cornwall (Forbes) ; there is, however, 

 no certamty that these were true Ech. melo. But Farran records 

 a specimen from 53° 1' N., 14° 34' W., 525 m. (" Helga "), which 

 is seen from the description to be a true Ech. melo. 



The species is elsewhere known from the Mediterranean, the 

 coasts of Portugal, and the Azores. Bathymetrical distribution 

 ca. 30-1100 m. 



5. Echinus elegans Diiben and Koren. (Fig. 139.) 



Test low, usually arched. Primary spines rather large, 

 forming — like the tubercles on the test — very distinct, regular 

 longitudinal series ; secondary spines and tubercles distinctly 

 smaller than the primaries. Each ambulacral plate carries a 

 primary spine (tubercle), the two series in each ambulacral area 

 being of equal size. No spines on the buccal plates. Globiferous 

 pedicellariae usually with 2-3 lateral teeth on each side of the 

 blade. Tridentate pedicellarise with fairly broad valves, of a size 

 up to 2 mm. length of head (Fig. 167, 2). Colour of the test 

 usually whitish, with a reddish tint on the upper side ; sometimes 

 violet. Spines exquisitely pink with white tip (not fading in 

 alcohol), or uniformly reddish or yellowish. Reaches a size of 

 ca. 80 mm. horizontal diameter. 



Biology and development unknown. 



In British seas this species has been found at various places 

 off the west coast of Ireland ^ and Scotland to north of the 

 Shetlands ; it is also recorded from the east coast of Scotland. 

 Apparently it is nowhere common. It is elsewhere known from 

 the Trondhjem Fjord and S. of Iceland to the Bay of Biscay and 

 the Azores ; its occurrence in the Mediterranean, as. also on the 



^ Partly recorded under the erroneous name Echinus gracilis (Diib. 

 and Kor.). 



