Arthroacantha, Williams. 273 



which must therefore be deleted. We have then the same 

 word for the two genera ; but in the one case it is placed in 

 the masculine and in the other in the feminine gender. It is 

 difficult to see the reason why Schmarda should have adopted 

 the masculine termination -iis instead of retaining the feminine 

 termination -fl of the Greek I'lKaidn, and exception might fairly 

 be taken to the change, and it would be open to any one to 

 alter the -us into -a, and thus corrected the word is precisely 

 identical with the corrected Arthracantha^ Williams. 

 Schmarda does not seem to have followed any rule respecting 

 the terminations of the generic names, for in tlie same group 

 he employs Ilexarthra^ Listrwn, and Typhlotrocha ; and it 

 may be urged that Agassiz has also modified the terminal -a 

 of the same Greek word into -us in the case of the numerous 

 genera of fossil fishes which are based upon spines. 



Admitting, however, that Arthr acanthus^ Schm., may be 

 retained in the masculine form, it seems to me that the later 

 term Arthracantha^ Will., judging according to the spirit of 

 the rule of the British Association, cannot be valid. It is 

 substantially the same word and unequivocally it has the 

 same meaning as Schmarda's term. To admit it would be 

 the same as allowing that the same Greek word would be 

 applicable to three distinct genera, according to its masculine, 

 feminine, or neuter termination ! 



Again, if the term were specially suitable to a genus of 

 Crinoids, one might be disposed to allow the infraction of the 

 rule in favour of retaining it ; but even Messrs. Waclismuth 

 and SjM'inger * are constrained to acknowledge that it is 

 " injudiciously chosen." 



These same authors, moreover, are not merely content with 

 endeavouring to upset the generic term Hyfftricrinus^ but 

 they also assert that the species which I described and figured 

 in the ' Annals ' as Hystricrinus Garpenteri is " probably a 

 synonym of A7-throacantha punctohracMata, Williams " ■\. 

 To this I reply that Prof. Williams never professed to describe, 

 and in fact did not describe, a species of this name, that the 

 name is a MS. one of Prof. Hall, and that until the forms 

 have been sufficiently described and published, the species 

 has no recognized existence and cannot be a synonym of 

 H. Garpenteri. 



Prof. Williams, in the paper referred to above, under the 

 title " On a Crinoid with movable Spines," described a 

 single species which he designated Arthroacantha ithacensis\. 

 He com]mred this species with a specimen in the Museum of 

 Cornell University, which had been photographed by Prof. 

 Hall, and the photograph, with the MS. name Platycrinus7 



* Op. cit. p. 116. t P. 110. 



X ' Proceedings American Philosophical Society,' 1883, p. 85. 



