Notes on Australian Polyplacophora. with 

 Descriptions of Three New Species and 

 Two New Varieties. 



By Edwin Ashby, F.L.S., M.B.O.U. 



[Read April 13, 1922.] 



Plate III. 



Genus Acanthochiton (Gray, 1821, em.). 



In our paper of October, 1898 (Trans. Roy. Soc. S. Austr.), 

 and subsequent papers. Dr. Torr and the writer followed Dr. 

 Pilsbry in adopting the name for this genus of A canthochitesj 

 Risso, 1826. 



In Proc. Mai. Soc, vol. xi., pt. ii., pp. 126 and 127, 

 June, 1914, Mr. Tom Iredale draws attention to the fact that 

 E. Gray's name of Acanthochitona (Lon. Med. Repos., vol. 

 XV., 1821) antedates Risso's name by five years, and he therein 

 also points out that in the name commonly used, Risso's 

 spelling has been amended. Iredale followed this in July, 

 1915 (Trans. N. Z'd Inst., vol. xlvii., p. 422, 1914), by 

 amending Gray's name in dropping the terminal "a" and 

 writing the genus "Acanthochiton (Gray, 1821, em.)". It 

 will also be seen that Dr. Pilsbry, I.e., while adhering to 

 Risso's name, gives "Acanthochiton, Herrmannsen, Indicis 

 Generum Malacozoorum Primordia, i., p. 2; Acanthochiton 

 of Carpenter and many modern authors." While several 

 Australian workers have adopted Gray's name in place of 

 Risso's, as pointed out by Iredale, I.e., it is regrettable that 

 they have not followed Iredale in the amended spelling, 

 changing Acanthochitona into Acanthochiton. 



In all my papers, in 1918 and since, I have adopted 

 Iredale's spelling for the following reasQns: — (1) The terminal 

 "Chiton" is in keeping with so many other genera. (2) The 

 two words, "Acantho" and "Chiton," are both masculine, 

 and Gray seems to have tacked on to these two Greek words 

 a Latin feminine terminal, thereby producing what my friend 

 the classical professor terms, a ''mongrel word." It is pos- 

 sible that Gray added the "a" to make his new genus agree 

 with a certain specific name, a course that can hardly be 

 justified; anyhow, I cannot see how we can do otherwise than 

 adopt Iredale's suggestion and drop the unfortunate terminal. 

 This course seems to be the commonsense one, and is probably 

 the only correct one, and, as Iredale says, there are plenty 

 of precedents. 



