ASTEROIDEA i49 



Anseropoda antarctica sp.nov. 

 (Fig. E, i-ic; Plate X, fig. 3 ; Plate XII, fig. i) 



Diagnosis. Rays 5. R 17 mm., r lo-ii mm., br 12-13 mm. (body distorted). 

 Broadly stellate, the general habit that of a thin-edged Asterina ; disk rather arched and 

 oral region sunken; interradial areas thin but restricted in extent. Abactinal surface 

 covered with small, uniform truncate granules, grouped so as to indicate underlying 

 plates; actinal plates with combs of usually 3 spinelets; adambulacral furrow combs 

 with 6-3 webbed, slender, blunt spinelets; subambulacral combs with 5-3 spinelets; 

 marginal oral spinelets 8, basally webbed. 



Description. The general form is more that of an Asterina than of a typical Ansero- 

 poda owing to the arched disk and concave actinal surface. The small size obviates an 

 extensive development of broad thin actinal interradial areas. 



The abactinal surface is covered with fairly uniform truncate granuliform spinelets, 

 o-i8-o-22 mm. long, the top of which is subcircular and armed with numerous thorn- 

 lets. A profile view is shown in fig. i. The granules, by reason of slightly diflrerentiated 

 spacing, form groups corresponding roughly to underlying plates, most conspicuous in 

 the interradial areas. Larger radial plates carry 12-18 granules; the smaller interradial 



plates 5 or 6. 



The abactinal plates are thin, scale-like and strongly imbricated, with a curved 

 external free edge. In the median radial series this edge is directed toward centre of 

 disk. The other plates are arranged in series parallel with the radial, and also in transverse 

 series ; and the curved free edge is toward centre of disk and radial line. On the coelomic 

 side the dorsolateral plates each have a conspicuous process which is directed toward the 

 margin of ray and increases in length in successive plates. This process is characteristic 

 of Anseropoda (fig. E, i a, i b). 



Papulae small, "here and there" on centre of disk, and in two radial series, one on 

 either side of carinal plates — about 12 to a series. 



Madreporite i mm. in diameter, situated 4 mm. from centre of disk. 



Superomarginal plates small, abactinal in position, the margin ray being defined by 

 the outer end of inferomarginals, which form a border outside of the superomarginals 

 nearly as wide as the latter. Superomarginals carry 10-12 granules and the abactinal 

 surface of the inferomarginals about the same number, a trifle smaller in size. There is a 

 distinct groove between the inferomarginals (or the lateral outgrowths of the imbricated 



plates proper). 



The actinal plates are in regular oblique transverse series corresponding each to an 

 inferomarginal (and usually to an adambulacral). The grooves, mentioned above, con- 

 tinue to the ambulacral furrow between the regular lines of actinal plates. A few plates 

 near the oral angle carry a central comb of 4 or 5 short sharp thorny spinelets, but 

 usually there are 3 in a slightly curved comb (1-3 in very small specimens, R 5 mm.). 

 Occasionally the spinelets stand in a group, spinelets 0-3-0-37 mm. long. 



