REPORT ON THE ASTEROIDEA. 103 



Actinal interradial areas small, with intermediate plates arranged in regular columns, 

 and bearing short skin-covered papillae, three or four larger than the rest in the midst, 

 forming a massive pedicellarian apparatus. 



Adambulacral plates large, and longer than broad. Adambulacral armature consisting 

 of short skin-covered spinelets, arranged in several longitudinal series, and one large pedi- 

 cellaria formed of three or four modified papillae. 



Madreporiform body large and compound. 



Anal aperture subcentral and distinct. 



There are no superambulacral plates, but a ridge on the ambulacral plate suggests 

 forcibly the appearance of a coalesced or incipient rudiment of that structure. 



Remarks. — This is a well-marked and readily distinguishable genus. Although an 

 unmistakable Archasterid, it may be said to hold a more or less intermediate position 

 between Dytaster and Leptopty 'chaster — a genus which I Lave for the present at least felt 

 warranted in ranking amongst the Astropectinidse. Its nearest affinities are with Dytaster, 

 but it is distinguished by the short, cylindrical, pointed rays, by the disproportionately 

 small supero-marginal plates, as well as by a number of minor characters, which, being 

 noted in the diagnosis above given, it is unnecessary to recapitulate. On the other hand, 

 Lonchotaster approaches Leptopty 'chaster by the short marginal plates and the small 

 superior series, but is widely separated from that form by the presence of the numerous 

 pedicellarise ; by the compound madreporiform body ; by the long, large, adambulacral 

 plates, with their longitudinally disposed armature ; and by the peculiar sacculate spinula- 

 tion. Lonchotaster is further characterised by the absence of superambulacral plates, 

 and by the unmistakable presence of an anal aperture. 



Chorology of the Genus Lonchotaster. 



«. Geographical distribution : — 



Atlantic : One species between the parallels of 20° and 30° N. 



Lonchotaster tartareus off the West Coast of Africa, between the 

 Canaries and the Cape Verde Islands. 



Southern Ocean : One species between the parallels of 60° and 70° S. 



Lonchotaster forcipifer in the neighbourhood of the pack ice 

 of the Antarctic Circle, near the meridian of 95° E. longitude. 

 It is also found South of Australia, near the meridian of 110° E. 

 longitude. 

 /3. Bathymetrical range: 1950 fathoms to 2400 fathoms. 



Both species are confined to the Abyssal zone. 

 y. Nature of the Sea-bottom : Lonchotaster tartareus is found on Globigerina ooze, 

 and Lonchotaster forcipifer on Diatom ooze. 



