66 NATURAL HISTORY BULLETIN 



Stegn ASTER WESSELi (Perrier) Sladen. 



Asterina wesseli Perrier, Arch. Zoiil. Exper. et Geu., vol. v, p. 231, 1876; 



Etoiles de Mer., p. 220, 1884. 

 Stegnaster wesseli Sladen, Voy. Chall., xxx„ p. 778, 1889. Verrill, op. cit., 



p. 481, 1913. 



Plate iii ; figures 3, 3a. 



The form is pentagonal with emarginate sides, or substellate, 

 with very short, wide rays. Radii of one of the larger speci- 

 mens, IG'^ and 20°™ ; ratio, 1 :1.5. No. 758, Yale. 



Central part of dorsal surface is convex. The dorsal surface 

 is everywhere covered with a granulated dermis, both on and be- 

 tween the plates. The granules are minute, but sharp and rough. 

 The larger plates of the papular areas are convex, curved and 

 deeply notched for the papular pores; in front of the notch is a 

 small ossicle, bordering the pore proximally. 



The interactinal plates are rather thick, closely imbricated, 

 and covered, together with their interspaces, by a sharply and 

 densely granulated dermis, which also invests the bases of the 

 row of minute spinules ; it also forms a continuous web nearly to 

 the tips of the marginal adambulacral spines, uniting them in an 

 uninterimpted series to the ends of the rays; it also covers the 

 jaws and peroral spines, the granules becoming there higher, 

 like small acute spinules. Many of the interactinal plates bear 

 a small transverse group or rudimentary fan of two to four very 

 small, sharp spinelets, which are much obscured by the sur- 

 rounding granulated skin. The granules are pointed, rough, 

 and crowded. 



The furrow-spines are sub-equal, slender, obtuse, mostly two 

 or three to a plate, standing in a nearly straight row. 



Dorso-ventral pillars or trabeculse are well developed, rather 

 stout, often curved. Jaw-spines form a continuous series with 

 about six or seven on each side, grading into and united with 

 the adambulacral row; apical ones stouter. No epioral spines 

 seen. A pair of small pores, probably genital, are situated in 

 each interactinal area, one on either side of the convex outer 

 end of the jaw-plates. 



The central part of the dorsal side of the disk is surrounded 

 by five larger and more prominent lunate plates, which are the 



