ASTEROIDEA 113 



Forma ceramoideus nov. (Plate I, figs. 3, 5, 6). 



Diagnosis. Differing from extreme examples of forma granidifenis in the arcuate, 

 stellate-pentagonal shape, and in having fewer, generally broader superomarginal 

 plates, which are always more or less convex and constitute, with the similar infero- 

 marginals, a thick frame enclosing the body. 



Type St WS 246. 



Remarks. The smallest specimen of iorma granulif ems has R 12-5 mm. and about the 

 same form as the adult. It would probably be difficult to distinguish from the young of 

 typical elongatus. There are 13 superomarginals, the same as in specimen K having 

 R 33-5 mm. The smallest specimen of ceramoideus has R 8-5 mm., 8 superomarginals 

 and a stellato-pentagonal form. It was taken at St. WS 825 along with specimen F, 

 which is something of an intergrade as regards the fewer, thick marginals (but is stellate 

 in form). 



Forma ceramoideus is easy to confuse with O. penicillatus forma grayi with which it is 

 sometimes associated. In ceramoideus (and granidiferus) the actinal spinelets of the oral 

 angles are gradually transformed into polygonal granules toward the inferomarginal 

 plates so that the actinal plates, for some distance back from the inferomarginals, are 

 armed with granules similar to those of the inferomarginals. In grayi all the actinal 

 plates are spinulose, and the inferomarginal armature is spinulose rather than granulose ; 

 the abactinal plates are distinctly tabulate and are, in fact, low paxillae. 



Type locality of Acodontaster elongatus granuliferus. 53° 13' S, 68° 31' W 

 (east coast of Tierra del Fuego), 97 m. (Mission Scientifique du Cap Horn, 1882-3). 



Distribution. Falkland Plateau; Cape region; north to Uruguay where A. glaber 

 (Barattini) may constitute a recognizable race. 



Acodontaster conspicuus (Koehler) 

 Pseudontaster conspicuus Koehler, 1920, p. 202, pi. 42, figs. 1-7; pi. 43, figs, i-io; pi. 70, fig. i.— 



1923, p. 88, pi. 13, figs. 4-6. 

 Acodontaster elongatus var. abbreviatiis Koehler, 1923, p. 81, pi. 10, figs. 1-3 (South Georgia, 24- 

 52 m.). 

 St. 42. Off mouth of Cumberland Bay, South Georgia, 120-204 m., 2 specimens. 

 St. 123. Off mouth of Cumberland Bay, South Georgia, 230-250 m., grey mud, i specimen. 

 St. 148. Off Cape Saunders, South Georgia, 132-148 m., grey mud and stones, i specimen. 

 St. 149. Mouth of East Cumberland Bay, South Georgia, 200-234 m., mud, i specimen, R 70 mm., 

 r 30 mm. 



St. WS 865. 50° 03' S, 64° 14' W, 126 m., I specimen, R 82 mm., r 36 mm. 



This species has been figured and described in detail by Koehler. It is characterized 

 by curious pedicellariae composed of 3 or 4 enlarged, flat-topped granules, which do not 

 protrude beyond the other granules, except on the actinal plates near the oral angle. 

 Here the actinal granules gradually lengthen into spinelets and the valves of the pedi- 

 cellariae likewise lengthen. They sometimes form a conical fascicle of 3 or 4 pointed 

 thickened spinelets ; or retain their characteristic shape, with longer valves (Koehler, 

 1920, pi. 43, fig. 9). 



