172 THE VOYAGE OF H.M.S. CHALLENGEB. 



Other Localities. — This species also occurs off the coast of Greenland, off the eastern 

 coast of North America, off the Scandinavian coast, off Spitzbergen and Nova Zembla, 

 and in the Barents Sea. 



Ctenodiscus corniculatus has been found in the fossil state by the late M. Sars 1 in the 

 older beds of the Postpliocene or Glacial formation of Norway, near Christiania. 



2. Ctenodiscus australis, Liitken (PL XXX. figs. 1-6). 



Ctenodiscus australis" (Loven, M.S.), Liitken, 1871, Vidensk. Medd. naturh. Foren. i Kjobenhavn, p. 238. 



Localities. — Station 313. Near the Atlantic entrance to the Straits of Magellan. 

 January 20, 1876. Lat. 52° 20' 0" S., long. 67° 39' 0" W. Depth 55 fathoms. Sand. 

 Bottom temperature 47°'8 Fahr. ; surface temperature 48°-2 Fahr. 



Station 320. South of Monte Video, off the mouth of the Rio de la Plata. February 

 14, 1876. Lat. 37° 17' 0" S., long. 53° 52' 0" W. Depth 600 fathoms. Green sand. 

 Bottom temperature 37 c '2 Fahr. ; surface temperature 67°'5 Fahr. 



Remarks. — This species is readily distinguished by the large paxillse, by the hidden 

 madreporite, and by the shorter but still well-defined rays, which are obtuse and rounded 

 at the extremity, with large supero-marginal plates there in comparison to those in the 

 other species. The margins of the disk and rays are thick, well-rounded, and tumid, the 

 supero-marginal plates being bevelled slightly towards the abactinal surface. The number 

 of marginal plates is less than in Ctenodiscus procurator, and the form altogether is of 

 much smaller habit. The small tubercle or spinelet at the junction of the supero-marginal 

 and infero-marginal plates is more or less aborted. 



In the examples from deeper water (Station 320, 600 fathoms) the shortness and the 

 obtuseness of the rays and the prominence of the epiproctal cone or peak in the centre of 

 the abactinal area is especially noticeable. 



One specimen from Station 313 (55 fathoms) is remarkable in being regularly four- 

 rayed, with a perfectly cruciform outline. There are four regular mouth-angles, and 

 nothing irregular is noticeable excepting a slight displacement and malformation in a 

 few of the marginal plates near the median interradial line in one interbrachial arc, pro- 

 bably marking the place of the aborted ray. When the starfish is oriented with the 

 madreporiform body in the right anterior interradium, it is the right posterior interradium 

 in which this irregularity occurs ; and the position of the displacement of plates appears 

 to indicate that it is the ray No. 5 which is aborted, the ray No. 1 being thus brought 

 into the position of the odd posterior interradium. 



1 Oversigfc af Norges Echinodernier, Christiania, 18G1, p. 144. 



2 This was a inuseuni-nanie given by Lov&i, and was adopted by Liitken on the understanding that the 

 species was being figured for the descriptive account of the voyage of the " Eugenie." This work has never 

 been completed, and is now discontinued. 



