8 TH. MORTENSEN, ECHINOIDEA. 



es diese Art ist, der mit Recht der LAMARCK'sche Name bispinosa zukommt». Unfor- 

 tunately this conviction came so late that Clark still uses the name Phyllacanthus 

 annulifera for this species in his paper on the Western Australian Echinoderms, 

 published in the same year, 1914, as was Döderlein's paper. 



In his »Report on the Sea-Lilies, Starfishes, Brittle-Stars and Sea-Urchins 

 obtained by the F. I. S. »Endeavour» on the coasts of Queensland, New South 

 Wales, Victoria, South Australia and Western Australian 1 H. L. Clark appears to 

 have finally accepted the interpretation of these species maintained by Döderlein 

 and myself, and also the litnitation of the genus Phyllacanthus maintained by us. 

 In the same time he points out, that the Stephanocidaris bispinosa of Agassiz is 

 identical with the Phyllacanthus australis of Ramsay, the species having thus to be 

 named Prionocidaris australis (Ramsay), the name Pr. Agassizi Döderlein becoming 

 a synonym of it. 



In ray »Echinoiden d. deutschen Siidpolar-Exped. « I established the genus 

 Plococidaris for the two species bispinosa (Lamck.) and verticillata (Lamck.). Döder- 

 lein (Ech. d. Aru-Inseln, p. 242) objects that the character of the presence or 

 absence of spöts on the collar of the radioles, which is the only essential mark of 

 distinction between Prionocidaris and Plococidaris, is too insufficient for generic distinc- 

 tion. I agree that it is an unessential character, but then it is a fact that among 

 the Cidarids apparently trivial differences in the radioles do afford very important 

 characters for the distinction of the genera (e. g. Calocidaris). In any case the 

 species bispinosa and verticillata form a separate group within the genus Prionocidaris, 

 and it is then rather a matter of convenience, whether we will regard such group 

 as a separate genus or not. If the var. elegans should prove to form a separate 

 species, that would be additional reason for keeping this group of species as a sepa- 

 rate genus or, at least, subgenus. For the present, however, I think it unnecessary 

 to maintain the genus Plococidaris, and agree with Döderlein in referring also the 

 species bispinosa and verticillata to the genus Prionocidaris. 



Herewith we have evidently at length come to an agreement and — it maj- 

 be expected — a final settlement of these vexating nomenclatural questions. The 

 species of the two genera Phyllacanthus and Prionocidaris are then the following. 



Phyllacanthus Bran dt. 



Genotype: imperialis (Lamck.) (Syn. dubia Brandt). 

 Other species: tenuispinus Woods; Thomasii A. Ag. & H. L. Clark ; 

 magnificus H. L. Clark; longispinus Mrtsn. 

 Prionocidaris A. Agassiz. 



Genotype: baculosa (Lamck.), with var. annulifera (Lamck.). 

 Other species: bispinosa (Lamck.) (non A. Ag.); australis (Ramsay) (syn. 

 bispinosa A. Ag., Agassizi Dörerlein); hawaiiensis (A. Ag. & H. L. 

 Clark); glandulosa (de Meijere) ; verticillata (Lamck.). 



1 Biological liesults of the Fishing Experiments carried on by the F. 1. S. »Endeavour» 1900—14. Vol. 

 IV. Part I. 1916. p. 96— 9S. 



