ASTEROIDEA 59 



2. Astropecten sphenoj^lax Bell.^ 



Upper marginal plates mostly with a larger, conical spine. 

 Lower marginals with an oblique series of ca. 10 long, slender 

 spines situated on a raised ridge, which gives the whole plate a 

 conspicuous wedge-shape. The surface of the marginals otherwise 

 closely covered with very fine, not flattened or scale -like, spinelets. 

 Lower marginals not regularly rectangular, but curving adorally 

 in their lower part. In the proximal part of arms upper and 

 lower marginals do not quite correspond, the lower being some- 

 what adorally displaced, the plates of the two series thus to some 

 degree alternating. Oral interradial areas with 2-3 series of 

 ventro- lateral plates, the inner series with 4-6 plates. Adam- 

 bulacral plates with 3 furrow spines. No pedicellarise. Colour in 

 life unknown. R = 4-5r. Largest size recorded 52 mm. R. 



Biology and development unknoA\Ti. 



This appears to be a rare species, having been found onty off 

 Blacksod Bay, Co. (ca. 900 m., " Fingal "), in the Bay of Biscay 

 (828 m.), and off the Azores (1187 m., " Princesse Alice "). 



2. Psilaster Sladen. 



Disk rather small ; arms high, with almost vertical sides, long, 

 narrow and pointed. Marginal plates high and narrow, covered 

 with fine grains, the lower with single larger spines, which lie 

 flat and do not form a marginal fringe. Oral interradial areas 

 fairly large, with 3-4 series of small plates, continuing to about 

 the middle of arm, separating the adambulacral from the lower 

 marginal plates. Madreporite naked. No pedicellarise. 



Only one species in European seas. 



L Psilaster andromeda (Miiller and Troschel). (Fig. 33.) 



(Sjm. Astropecten andromeda Miill. and Trosch.) 



Marginal plates only partly covered with fine grains or small, 

 scale-like spines, these being in the main confined to the edge of 

 the plates, leaving a median part naked. The larger spines on 

 the lower marginals in a vertical series along the outer edge. 

 Adambulacral plates somewhat projecting in the furrow, carrying 



^ No very good figure exists of this species. The present author having 

 had the opportunity of examining only one poorly preserved specimen, 

 must refer to the figures given on PI. XI in Bell's Catalogue ; the Fig. 2 on 

 that plate gives a rather good impression of the peculiar wedge-shape of 

 the lower marginals. 



