464 THE VOYAGE OF H.M.S. CHALLENGER. 



y8. Bathymetrical range: 101 to 632 fathoms. 



y. Nature of the Sea-bottom : Brown mud (Payer) ; Coarse granular clay, and grey 

 sandy clay (Danielssen and Koren). 



Cliorological Synopsis of the Species. 



1. Korethraster hispidus, AVyville Thomson (PI. LXXX. figs. 6-9). 



Korethraster hispidus, Wyville Thomson, 1873, The Depths of the Sea, pp. 119, 120, fig. 15. 1 



Locality. — " Porcupine " Expedition : 



Station 57, 1869. In the Faeroe Channel. Lat. 60° 14' N., long. 6° 17' W. Depth 

 632 fathoms. Bottom temperature — o- 8 C. ; surface temperature 11°"1 C. 



Remarks. — This species has been so fully and ably described by Danielssen aud Koren, 1 

 and previously by von Marenzeller, 2 that I consider it superfluous to re-describe the 

 species. Through the kindness of Dr von Marenzeller I have examined the example col- 

 lected during the " Tegetthoff " Expedition by Mr Julius Payer, and I can confirm the 

 accuracy of his determination. I have therefore limited myself to giving an illustration 

 of the original example dredged by the " Porcupine " ; and I have included in the fore- 

 going generic diagnosis reference to several points of structure which appear to have escaped 

 the notice of previous observers. 



Genus Peribolaster, Sladen. 

 Peribolaster, Sladen in Narr. Chall. Exp., 1885, vol. i. p. 616. 



Form stellate. Pays rather short and broad. Disk large, more or less inflated. 

 Abactinal surface convex. Actinal surface plane. Margin angular. Interbrachial arcs 

 acute. 



Abactinal surface with cruciform plates having delicate prolongations or supplementary 

 trabeculse, which impinge on the adjacent plates, and form a regular network with large 

 quadrangular meshes over the entire surface. On the centre of each abactinal plate is 

 borne on a small boss a fascicule of delicate, equal spinelets, the spinelets being enveloped 

 in membranous sheaths which are united in the interior of the fascicule. The fascicules 

 are isolated and well spaced. Several papulae are present in each interspace or mesh. 



1 DenNorske Nordhavs-Expedition 1876-1878, Zoologi, xi. Asteroidea, 1884, p. 95, tab. xii. 



2 DenJcschr. d. k. Alcad. d. Wiss. Wien, math.-naturw. CI., 1877, Bd. xxxv., p. 283. 



