332 ECHINODERMS OF THE BRITISH ISLES 



Iieight about midway between the apical system and the posterior 

 end, the posterior interambulacrum being rather elevated. The 

 paired interambulacra with a number of somewhat larger tubercles 

 above the ambitus, and witli corres])()nding longer spines among 

 the general short, uniform covering of spines ; these longer spines 

 are, however, less conspicuous than the larger tubercles on the 

 denuded test. The labrum reaches to the second adjoining 

 ambulacral plates. The pedicellarise partly very characteristic ; 

 the globiferous — w'hich have been found only in specimens from 

 the Mediterranean — are very conspicuous, with a thick, brownish 

 head and a thick stalk with a whorl of freely projecting rods 

 (Fig. 195, 2) ; the valves have 5-6 teeth along each side of the 

 terminal opening. The tridentate pedicellarise (Fig. 195, 1) have 

 leaf -shaped valves, with the edges of the lower part of the blade 



Fig. 194. — 1-2. Echinocardium cordatum, upper side ; 1, covered with 

 its spines ; 2, the denuded test. 3. Echinocardium flavescens ; de- 

 nuded test, upper side. The figures show the inner fasciole distinctly. 

 Slightly reduced in size. (From Danmark's Fauna.) 



irregularly serrate ; the triphyllous pedicellariae (Fig. 197, 1) 

 have a series of broad teeth inside the edge. Reaches a size of 

 ca. 90 mm. length of test. 



Lives mainly on sandy bottom, buried ca. 15-20 cm. deep in 

 the ground ; a channel leads from the hole to the surface of the 

 ground. The slime secreted by the spines glues the sand grains 

 together, the animal lying free in the hole, not directly in 

 touch with the sand. It is said to take the food particles from 

 the surface of the sand by means of the exceedingly extensile 

 tube-feet of the frontal ambulacrum, which drag them down into 

 the hole to the under side of the animal, where the penicillate 

 tube -feet around the mouth catch the particles and put them 

 into the mouth. In any case the opinion held formerly that 

 this species, and the Spatangoids generally, get their food 

 by the bottom material being automatically pushed into the 

 mouth as the animal bores through the sand does not hold 



