58 ECHINODERMS OF THE BRITISH ISLES 



pentacanthus (D. Ch.), entirely lacking the large spine on the 

 upper marginals, and var. serratas (Muller and Troschel), which 

 has several larger spines (3-5) on the upper marginals. 



The larva is a Bipinnaria with short arms ^ ; it has no 

 Brachiolaria stage (Fig. 28, 3). 



It is a very voracious species, feeding mainly on various 

 molluscs, crustaceans, echinoderms, annelids, and appears to be 

 a noticeable competitor for the food of the plaice. The animals 

 that make its food are swallowed whole. Even small fishes it 



Fig. 32. — Astropecteti irregularis. Dorsal side. Nat. size. 

 (From Danmark' s Fauna.) 



eats, though it is probably able to catch only such specimens as 

 are not in a healthy condition and therefore unable to escape. ^ 

 It prefers a sandy bottom, in which it buries itself so as to lie 

 concealed. 



Common all round the British coasts. It is distributed from 

 Lofoten on the Norwegian coast to Morocco, probably even to 

 the Cape Verde Islands. In the Mediterranean the var. penta- 

 canthus alone occurs. Bathymetrical distribution, ca. 10-1000 m. 



^ Figures of the younger stages of the Astropecten irregularis larva are 

 given in H. E. Newth's paper, " The early development of Astropecten 

 irregularis ", Quart. Journ. Micr. Sc. 69, 1925, PI. 41. 



2 The author has observed that a specimen of Amphiura Chiajei, which 

 was removed from the stomach of an Astropecten irregularis eighteen hours 

 after this latter was caught, was still alive, though the skin and the tube- 

 feet had been digested. It was still alive after two days, and had begun 

 to regenerate its tube-feet. Probably it would have recovered completely 

 if the experiment had not been discontinued. 



