5G8 THE VOYAGE OF H.M.S. CHALLENGER. 



A. Aster las rubens group : Asterias vera. 



1. Asterias vesiculosa, n. sp. (Pi. XCIX. figs. 1 and 2 ; PI. CIII. figs. 9 and 10). 



Rays six. E = 81 mm. ; /■= 16 mm. R>5 r. Breadth of a ray at the base, 15 to 

 16 mm. ; breadth about midway between the disk and the extremity, 9 mm. 



Pays elongate, subdepressed, tapering from the base to the extremity, the outer part 

 of the ray being narrow and rather attenuate. Disk subdepressed, only slightly inflated ; 

 abactinal surface of the rays slightly convex, also slightly convex at the base on the actinal 

 surface, the disk being marked with depressions in the actinal interradial lines. Inter- 

 brachial arcs acutely angular. 



The abactinal plates are entirely masked. The whole area is beset with isolated, widely 

 spaced, short, robust, obtuse spinelets, each of which is encircled by, and appears to pro- 

 trude through, a widely expanded puffy vesicle. Occasionally one or more rather large 

 pedicellarise may be imbedded. No definite order of arrangement can be detected in the 

 disposition of the spinelets. The interspaces between the vesicles are closely crowded 

 with numerous large papulae, amongst which pedicellarise are occasionally interspersed, 

 and sometimes the latter are borne on a vesicle resembling in miniature that of the 

 spinelets. Viewed with the naked eye the whole abactinal surface has a coarse, irregularly 

 granular and studded appearance. 



The armature of the adambulacral plates consists of two short, robust, cylindrical, 

 slightly tapering, obtuse spinelets, which form two regular longitudinal rows. At the base 

 of the innermost spine, and quite within the furrow, are numerous very large forficiform 

 pedicellarise. External to the adambulacral plates is a rather wide space covered with a 

 thick, puffy, wrinkled membrane, through which protrude a single longitudinal series of 

 widely spaced and rather large papulae, and this space is bounded at the margin of the 

 actinal area by a longitudinal series of plates (probably the representatives of infero- 

 marginal plates) upon which are borne one or usually two diagonally placed small 

 spinelets,. almost hidden in an expansive vesicle beset with isolated pedicellarise. Above 

 this series of infero-marginal plates is a wide area which occupies the lateral wall of 

 the rays, covered with thick wrinkled skin, punctured with rather numerous papulae, and 

 bearing, at least near the base of the rays, large forficiform pedicellariae. It is bounded 

 superiorly by a regular longitudinal series of plates — the representatives of the super- 

 marginal series — upon each of which is borne a single rather small spinelet, surrounded 

 by a large, widely expanded vesicle in which are imbedded from three to five pedicellarise. 

 Here and there upon the abactinal surface and elsewhere may be seen isolated and very 

 large forficiform pedicellariae usually on a vesicular base. 



The madreporiform body, which is situated about midway between the centre of the 

 disk and the margin, has its surface grooved with fine convoluted striations. 



