1893.] PROF. BELL OS ODONTASTBR AND THB ALLIED GBNEEA. 259 



3. Oil Odontaster and the Allied or Synonymous Genera 

 of Asteroid Echiuoderms. By P. Jeffrey Bell^ M.A., 

 Sec.R.M.S. 



[Eeceived February 27, 1893.] 



Although I have no intention of pursuing as far as I logically 

 should an investigation which would carry one deep into the per- 

 plexities of the classification of the Asteroidea, it seems advisable 

 to say a few words as to Odontaster. 



As defined by Prof. Verrill in 1880% the characters of this 

 genus are, perhaps, a little obscure ; Mr. Sladen" says of it: — " I 

 have great hesitation in placing Odontaster with the Archasteridse ; 

 it may possibly prove to be more closely allied to the Pentagon- 

 asteridai ; in any case it appears to be an annectant genus between 

 the two groups." 



An important character in Odontaster is the possession of a 

 " large, strong, sharp, erect or everted tooth." 



Among the new genera of Pentagonasteridge described in the 

 'Challenger' Eeport, one, Gnathaster, has the "mouth-plates 

 with a prominent keel, developed aborally into a hyaline spiniform 

 prolongation ; " but no ground is given for suspecting that there 

 is any relationship to Odontaster. 



In his interesting and instructive Report on the Starfishes of the 

 Mission to Cape Horn, Prof. Perrier diagnoses a new genus, which 

 he calls Asterodon ; the " pieces deutaires " in species of this genus 

 carry " chacune un grand piquant vitreux refiechi en dehors " or 

 support " ensemble un piquant impair, unique, vitreux, interradial" 

 {op. cit. p. K. 132). This genus, though " with an apparent 

 resemblance to the Pentagonasterida;, is regarded as, on the whole, 

 haviug more affinity with the Archasteridse, and reference is made, 

 on the page cited, to Verrill's Odontaster. On p. K. 188 of the 

 same memoir, Prof. Perrier makes some remarks on the genus 

 Gnathaster, which he finds to be synonymous with, and to have 

 priority as a name over, Asterodon — unless, he adds, " les Odontaster 

 de M. Verrill ne soient des formes generiques identiques, ce qui 

 parait vraisemblable." 



More fortunate than either Prof. Perrier or Mr. Sladen, I have 

 been able to make a study of specimens of Odontaster hispidus, 

 presented to the Trustees of the British Museum by the United 

 States National Museum and authenticated by its authority. It 

 soon became obvious that M. Perrier's supposition was correct, 

 and the three names, therefore, are synonyms, Odontaster having 

 a priority of nine years. 



Like the English observer, the French one remarks that the 

 forms of this genus are " manifestement des formes de passage." 

 But while the former places his genus with the Pentagonasteridae, 

 the latter assigns his to the Archasterida?. 



1 Amer. Journ. Sci. xx. (1880) p. 402. ^ Chull. Rep. Aat. (1889) p. xxii. 



