420 Transactions. 



Ischnochiton maorianus Iredale, 1914. [P. 9.] 



In the Proc. Mai. Soc. (Lond.), vol. xi, p. 36, 1914, I proposed this name 

 for the common New Zealand species known as /. longicymba Quoy and 

 Gaimard, 1835. 



In the Diet. Sci. Nat. (Levrault), vol. xxxvi, 1825, Blainville furnished 

 the first systematic monograph of this order, and on p. 542 described Chiton 

 longicymba from specimens collected at King Island, Bass Strait. In 1835, 

 as quoted by Suter, Quoy and Gaimard figured a shell under Blainville's 

 name, giving as localities New Zealand and Australia. 



In the Manual Conch., vol. xiv, p. 87, 1892, Pilsbry detailed the differ- 

 ences between the shells thus named from Australia and New Zealand, 

 and, ignoring Blainville's name, used Quoy and Gaimard's misinterpretation, 

 further making confusion by restricting the name to the New Zealand form. 

 It is unjustifiable to transfer names in this manner, and the only way out 

 was to name the New Zealand species as I have done. 



Acanthochiton australis (Suter, 1907). [P. 16.] 



Suter described a Mopalia australis from the Snares Islands. Geo- 

 graphically the generic location was extraordinary, and it has now been 

 proved that the genera of Chitons are restricted to certain geographical 

 areas. Thiele, from this reasoning, threw doubt upon the accuracy of 

 Suter's selection. I have been puzzled, but now put forward the solution. 

 The description given by Suter agrees in every detail, save the number 

 of slits in the anterior valve, with Acanthochiton. The normal number of 

 slits in that genus is five, and any larger number is due to interslitting. 

 Consequently the eight recorded by Suter is quite abnormal, and misled 

 him owing to the eroded nature of the exterior. Had the sculpture been 

 observed, it is almost certain that the true generic location would have 

 been ascertained at first. 



Plaxiphora aurata (Spalowsky, 1795). [P. 18.] 



In the Proc. Mai. Soc. (Lond.), vol. xi, p. 31, 1914, I noted that 

 P. aucklandica Suter was based upon a juvenile of P. campbelli Filhol. I 

 now put forward the above as the correct name for a species which has the 

 longest synonymy of any austral Chiton, and yet is the best-marked species. 



In the Proc. Mai. Soc. (Lond.), vol. ix, 1910, I synonymized P. superba 

 Pilsbry and P. subatrata (Pilsbry) Suter with the earlier P. campbelli Filhol. 

 These names refer to Neozelanic shells. On the next page I pointed out 

 that P. carmichaelis (Wood) should be used for the South American species 

 commonly known as P. setiger King, and also recorded as a synonym 

 C. hahni Eochebrune. The following year Pilsbry (" Nautilus," vol. xxv, 

 p. 36, 1911) showed that Chiton auratus Spalowsky (Prodr. Syst. Hist. 

 Test., p. 88, pi. 13, figs. 6a, 6& ; 1795) antedated both, and though described 

 from " Die Siidsee (von der Insel Otahaiti ?) " was undoubtedly the South 

 American shell. I have examined large numbers of the latter in every 

 stage of growth and preservation, and I cannot distinguish any differential 

 characters between them and the Neozelanic shell. It should be remarked 

 that hitherto no one has critically compared the two species. Pilsbry 

 only knew the Neozelanic form from Carpenter's notes, and Suter never 

 mentions the South American species in connection with it. A parallel 

 distributional case is the admission of Callochiton puniceus Gould, a common 

 South American shell, to the New Zealand Chiton fauna (p. 14). Suter 



