STARFISHES OF THE PHILIPPINE SEAS. 261 



Genus NYMPHASTER Sladen. 



Nymphaster Sladen, 1885, p. 612 ; 1889, p. 294. Type, N. protentus Sladen. 



by designation, Fisher, 1917. 

 Dorigona PKrauEii (not Gray), 18S5, p. 39; 1S94. p. 3G5.— Koehi.ee, 1909, 



p. 54 ; 1910o, p. 60. 



Diagnosis. — Goniasteridae with long rays, composed dorsally of 

 the superomarginals only; with low, not markedly tabulate, granu- 

 late, abactinal plates; actinal interradial areas large, granulate; 

 adambulacral plates with the furrow margin strongly angular, at 

 least on plates of distal half of ray, the angular furrow series sepa- 

 rating consecutive pairs of tube feet; pedicellariae spatulate, en- 

 trenched, or composed of more or less modified granules; no super- 

 ambulacral ossicles; no internal supplementary abactinal ossicles; 

 gonads in a single tuft on either side of the membranous interbrachial 

 septum. 



Remarhs. — This genus differs from Rosaster and Mediaster in 

 lacking internal abactinal ossicles connecting the plates of the papu- 

 lar areas, and in having the gonads in a single tuft, not serially 

 arranged. It differs further in the form of the adambulacral plates 

 and armature. Mediaster has superambulacral ossicles, not found in 

 Nymphaster. Nymphaster differs from Ceramaster in having single 

 gonads on either side of each interbrachial septum, angular adambu- 

 lacral plates, long rays, and in having low, not tabulate abactinal 

 plates. 



In his diagnosis of the genus, Sladen did not mention any specific 

 names, so that, under existing rules of nomenclature, the genus should 

 date from the Challenger report of 1889. Here no type is indicated, 

 and none has been designated. The following species are described : 

 symbolicus, hipunctus^ protentus^ alhidits, hasilicus. In 1899 Verrill 

 set aside symbolicus and hipwictus under the name Nereidaster. 

 This group, which is more nearh^ related to Mediaster than to 

 Nymphaster.^ falls within the genus Rosaster Perrier, 1894. The 

 type of Nympliaster must be chosen from the three remaining species, 

 and for this purpose Nymphaster protentus is best adapted. 



Koehler (1910a, p. 60) has proposed to limit the name Nymphaster 

 " to the forms in which the superomarginals are separated by a series 

 of abactinal plates and' to reserve the name of Dorigona for those in 

 which the marginal plates are contiguous." This course is not pos- 

 sible, because Verrill has already limited Nymphaster to the genus 

 which Koehler, following Perrier, calls '"'' Dorigona.'''' The genus 

 which Koehler calls " Nymphaster " is that previously named 

 Nereidaster (type N. symbolicus) by Verrill, which in turn is con- 

 generic with the earlier Rosaster of Perrier (type Pentagonaster 

 alexandri) . 



13434— Bill 1. 100—19 18 



