570 



THE VOYAGE OF H.M.S. CHALLENGER. 



4. Asterias torquata, n. sp. (PI. CII. figs. 1-4). 



Bays five. R = 76 mm. ; r — 9 mm. R > 8 r. Breadth of a ray at the base, 11 "5 

 mm. ; 1 tread th at 10 mm. from the base, 15 "5 mm., and midway between the disk and the 

 extremity, 14 mm. 



Rays long in proportion to the disk, broad and stout, tapering very slightly on the 

 inner two-thirds, then rather rapidly on the outer third ; abruptly constricted laterally at 

 the base, where the rays appear crushed together and give at first sight a false appearance 

 of a larger size to the disk than is actually the case. Junction of the base and disk 

 marked abactinally by a slight depression, where the rays easily separate. 



The abactinal area is beset with plates which bear single, isolated, short, robust 

 spinelets, very slightly tapering and obtusely rounded at the tip. The spines are covered 

 fully half their length with a thick membranous sheath which rises perpendicularly and 

 terminates abruptly, and its free margin is beset with a regular circlet of large uniform 

 forcipiform pedicellarias. Occasionally round the large spines the circlet may be doubled 

 or a few additional pedicellarise may be present. The spines are widely spaced, and the 

 intervening membrane is naked. It is punctured by numerous papulas in groups of 

 four or five. In some examples the median radial series of plates is distinctly traceable, 

 and may be even conspicuous, in consequence of the presence of two or three spiuelets on 

 a plate placed in line transverse to the direction of the ray. 



The armature of the adambulacral plates consists of two short, rather delicate, slightly 

 tapering, obtusely-tipped, equal spinelets, which form two longitudinal rows. No pedicel- 

 larise are present. Immediately external to the adambulacral plates is a slightly oblique 

 transverse series of three equal spinelets borne on an actinal plate (? infero-marginal) 

 which form three longitudinal rows. The spinelets are spaced apart, but rather 

 closely ; they are rather longer and much more robust than the armature of the adambu- 

 lacral plates, slightly tapering and obtusely tipped, and each is covered with a membranous 

 sheath which extends nearly to the tip, terminates abruptly, and bears on the margin at 

 the outer side of the spine a few forcipiform pedicellarise which are most numerous on the 

 outermost of the three spinelets. This series of spinelets is separated by a very narrow 

 space occupied by papulae, and at wide intervals apart, on the inner part of the ray, by an 

 occasional rather large forficiform pedicellaria, from a subregular longitudinal series of 

 spinelets, which is perhaps the representative of a supero-marginal series, but is in no way 

 distinguishable from the spinelets of the abactinal plates generally, excepting in its more 

 regular longitudinal disposition. 



The actinal interradial regions are narrow and devoid of spinelets, but may bear one or 

 more forficiform pedicellarise. 



The madreporiform body is distinct and situated close to the margin ; it is surrounded by 

 a circlet of well-spaced spinelets, similar in all respects to those on the abactinal surface gene- 

 rally, with sheath and pedicellariae. Its surface is grooved with fine convoluted striations. 



