40 



Notes on Some Western Australian Chitons 

 (polyplacophora), with additions to the fauna 

 and the Description of a New Species of 



RHYSSOPL.AX. 



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



[Read May 12, 1921.] 

 Plate VIII. 



Visiting Western Australia in connection with the Con- 

 gress of the Royal Australian Ornithologists' Union, in 

 October, 1920, I determined to take the opportunity of visit- 

 ing Ellensbrook, in the south-west corner of that State, during 

 the series of low tides at the end of the month. 



Dr. W. G. Torr had done some excellent collecting at 

 that locality at the end of December, 1910, obtaining single 

 examples of two striking and new forms which he described 

 under the names of Ischnochiton verconis and Tonicia 

 huUianus. It was in the hope of refmding these, and possibly 

 adding further species to the fauna of the State, that we 

 arranged this visit. Unfortunately a heavy westerly gale was 

 blowing during the two days spent at Yallingup, and still 

 heavier seas were coming in during the three days spent at 

 Ellensbrook, entirely precluding any effective work being done 

 at the latter locality. 



The work of the two days spent at Yallingup was carried 

 out under great difficulties, and while the number of speci- 

 mens taken was in consequence very limited, several forms of 

 exceptional interest were secured, and amongst them the 

 second known specimen of Dr. Torr's Tonicia huUianus. The 

 rocks are granitic and suited to the habits of chitons. 



My warmest thanks are also due to my colleague, Mr. 

 R. Wilson, of Eden Hills, but for whose able assistance the 

 results would have been much poorer. My stay in that 

 State was prolonged till the next series of low tides, and 

 Geraldton, 306 miles, by rail, north of Perth, and Dongarra, 

 40 miles to the south of that place, were both visited and 

 the reefs examined for chitons. Unfortunately the rocks in 

 both localities are composed of solid limestone reefs, with 

 rough surfaces, unsuited to the habits of this group of mol- 

 lusca, consequently very few species were secured, but amongst 

 them, fortunately, were two specimens of a new Rhyssovlax 

 which I propose to name B. Geraldtonensis, after the locality 

 where it was found. 



