66 



Notes on Australian Polyplacophora, including 

 Descriptions of two New Genera, a New Variety, 

 and the Description and Proposed Recognition 

 of Mr. Bednall's Stenochiton pilsbryanus. 



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

 [Read July 11, 1913.] 



Plate *XI. 



ISCHNOCHITONID AE . 



Genus Stenochiton. 



Zostericola, ii. subgen. 



Differs from. Stenochiton (sensu stricto) in that the shell 

 is short and broad instead of being elongated and narrow. 

 It possesses the highly polished and unsculptured surface and 

 minute girdle scales so distinctive of the true Stenochiton. It 

 also lives on the same order of plants (Fluviales) or sea grasses. 



The writer foreshadowed the establishment of this genus 

 in the paper on Steno chitons (Trans. Roy. Soc. S. Austr., 

 vol. xlii., 1918), and included the subgeneric name of 

 Zostericola in the distribution list published in the same 

 number of the Transactions. 



The name Zostericola is derived from the name of the 

 genus of plants upon which it is said to have been found, and 

 upon which it no doubt lives. 



Type Stenochiton pilsbryanus, Bednall. 



Zostericola pilsbryanus, Bednall. 

 Introduction. — In my monograph on the genus Steno- 

 chiton, mentioned above, I referred to the impossibility of 

 reconciling any of the known species with Mr. Bednall's 

 descriptions and drawings of Stenochiton pilsbryanus (Proc. 

 Mai Soc, vol. ii., pt. 4, 1897). I trusted that the type would 

 have reached Mr. Iredale in London safely, as only by 

 reference to the type could the matter be cleared up. Mr. 

 Iredale writes me (February 16, 1919), "I think you are right 

 in naming the shell that has been called pilsbryanus. I queried 

 it, as it did not agree with Bednall's figures at all. However, 

 no Stenochiton seemed like that figure. The type seems 

 missing, as the specimens I have marked 'type' do not agree 

 with the figure, nor have I seen the dissections." Thus no 

 help towards the elucidation of the problem is likely to come 



