36 " ENDEAVOUK " SCIENTIFIC RESULTS. 



Genus Nymphaster, Sladen. 

 As regards the generic name, it is to be regretted that 

 Koehler still persists in using Dorigona in place of Nymphaster^ 

 Sladen, in 1889, Verrill, in 1899, and Fisher more recently, 

 have pointed out that Dorigona is not one of Perrier's genera, 

 but dates back to Gray. Its type is either D. reevesii, Gray or 

 D. longimana (Mobius) ; no other species can be the type since 

 these are the only species mentioned by Gray, who, however, 

 designated no type. It has been shown, and, so far as I know, 

 never questioned, that D. reevesii, Gray is synonymous with 

 Goniodiscus capella, Miiller and Troschel, 1842. Now von 

 Martens constituted a subgenus, Ogmaster, for G. capella in 

 1865, a year before Gray proposed Dorigona. All later writers 

 have agreed that G. capella is entitled to generic rank and, 

 including Koehler himself, use Ogmaster capella as the correct 

 combination. Hence Dorigona longimana (Mobius) must be 

 the type of Dorigona, and I am quite unable to see why Sladen 

 should have dehberately replaced Gray's name with one of his 

 own coining, Iconaster. So far as I can see Iconaster is a pure 

 synonym of Dorigona, which is a monotypic genus with 

 Astrogonium longimanum, Mobius, as its type. 



It is evident then that A^ymphaster and Dorigona are not in 

 any way equivalent terms. Koehler proposes to restrict Nym- 

 phaster to the forms in which the superomarginal plates are 

 separated by a single median row of abactinal plates and use 

 Dorigona for the forms in which the superomarginal plates are 

 in contact dorsally. It is, of course, obvious that Dorigona 

 cannot be used in any such way. Moreover Verrill, in 1899, 

 proposed Nereidaster for the species with separated supero- 

 marginals, and restricted Nymphaster to the species which 

 Koehler would call Dorigona. This he was perfectly justified 

 in doing, for Sladen designated no type for the genus in which 

 he included five species. Clearly Dorigona, Koehler, is a 

 perfect synonym of Sladen's Nymphaster as restricted by 

 Verrill, and has no close relationship to Dorigona, Gray. It 

 is to be hoped, therefore, that our able and honoured French 

 colleague will no longer reject Nymphaster and will confine 

 Dorigona to Mobius' remarkable species. 



Nymphaster pentagonus,i sp. nov. 

 (Plate VIII., fig. 1-2.) 



R = 60 mm. or thereabouts ; r=18 mm. ; R=3.3 r. Br= 

 10 mm. ; R=6 br. Br at middle of ray, 6 mm. ; at tip, 



1. Pentagonus =-vi\th. five angles, or, as usually understood, five-sided » 

 in reference to the nearly straight-sided area of abactinal plates. 



