94 



ECHINODERMS OF THE BRITISH ISLES 



surface, forming two longitudinal series along each side of the 

 ambulacral furrow. R=I-2-l-4 r. Appears to reach only a 

 small size ; not known to exceed ca. 20 mm. diameter. Colour in 

 life, red or yellowish -red. 



Biology and development unknown. 



In British seas this species has been found only once, 56° 15' N., 

 11° 25' W., 2487 m. ("Porcupine"). Otherwise known only 

 from the Mediterranean from ca. 50-600 m. 



F'iG. 54. — Marginaster capreensis, oral and dorsal side. One interradius 

 has been denuded so as to show the skeletal plates. Slightly reduced. 

 (From Marenzeller. ) 



The form described by Perrier under the name of Margin- 

 aster pentagomis (Bay of Biscay, 400 m.) is distinguished from 

 M. capreensis by having numerous small spines on the dorsal 

 plates and (2) 3 outer spines on the adambulacrals. This 

 may perhayjs prove to be a distinct species ; however, so long 

 as only the single small type-specimen is known (R = 3 mm.) it 

 must be left undecided, whether it is a separate species or only 

 a synonym of M. capreensis. If a distinct species it may well 

 be expected to occur also in British seas. 



II. Order. Spinulosa Perrier. 



Marginal plates generally inconspicuous, not forming a 

 vertical edge to the disk. Dorsal and oral side covered with 

 spines, mostly" in groups on prominences from the plates, forming 

 paxill?e, more rarely isolated. Sim]:)lc pedicellariae may occur (in 

 the family Asterinida3). Papulae mostly both on the dorsal and 

 ventral side. Tube-feet, with a single exception, in two series, 



