338 PROCEEDINGS OF THE ACADEMY OP [1885. 



Family VLL— HEXACRINIDJE W. and Sp. 

 HEXACRINUS Austin. Rev. ii, p. 78. 



Additional species : — 



1884. H. minor (Dewalque MS.), Fraipont, Extrait des Ann. de la Soc. g6ol. de Belg., 

 Tome xi, p. 110, PI. 1, figs. 4 a and 4 b. — Devon, superieur. Senzeille, Bel- 

 gium. 



1884. H. verucosus (Dewalque MS.), Fraipont, Ibid., p. 108, PI. 1, fig. 3. — Devon, 

 auperieur. Senzeille, Belgium. 



1S82. H. Wachsmuthi Oehlert, Bull. g6ol. de France (Ser. 3), Tome x. p. 355, PI. 8, 

 fig. 3. — Devon, inferieur. Sabre and La Fleche, France. 



ARTHROACANTHA Williams. 



18S3. Williams, Proc. Am. Phil. Soc. (April), p. 84. 



Syn. Hystricrinus Hinde, 1885, Ann. and Mag. Nat. Hist. (March), 

 p. 158. 



Prof. Williams proposed the name Arthroacantha in 1883, for 

 a Crinoid of the Hexacrinus type -with movable spines, of which 

 he described and figured one species, A. Ithacensis, from the 

 Chemung of New York. He also defined the characters of 

 another species, from the Hamilton group, which had been named 

 by Hall as Platycrinus punctobrachiatus, but not defined by him, 

 except through the medium of a photograph privately distributed. 

 To the latter species Williams gave the name Arthroacantha 

 punctobrachiata. 



In 1885, Dr. Hinde (Ann. and Mag. Nat. Hist., p. 158), proposed 

 the name Hystricrinus for the genus defined by Williams, and 

 described and figured a species, H. Carpenteri, from specimens 

 derived from the Hamilton group of Ontario, Canada. He states 

 that eminent authorities decided Williams' name to be invalid, by 

 reason of its similarity to Arthr acanthus, previously emplo}'ed by 

 Schmarda for a genus of Rotatoria. Examination of the question 

 in the light of the Rules of the British Association, adopted in 

 1865, has led us to the conclusion that Arthroacantha, however 

 injudiciously chosen to designate a genus of Crinoid, will have to 

 stand. The tenth Rule (Am. Jour. Sci., July, 1869, p. 101) says : 

 "A name should be changed which has before been proposed for 

 some other genus in zoology or botany." It is evident from this 

 that a proposed name may be ignored on account of identity with 

 a prior name, but not by reason of mere similarity or resemblance 



