49 



R. tricostalis, which loves the exposed sides of clean hard 

 rocks. 



In conclusion. — It will be seen by the foregoing that the 

 following must be added to the Western Australian fauna : — 

 Acanthochiton kimberi, Torr; Kopionella matthewsi, Ire.; 

 and Rhyssoplax geraldtonensis, Ashby. That the following 

 must be removed from that list, viz. : — Plaxiphora hedleyi, 

 Torr, which become a subspecies of Kopionella matthewsi, 

 Ire. ; Plaxiphora zebra, Torr, becomes a synonym of the same 

 species; and Plaxiphora pusiulosa, Torr, becomes a synonym 

 of Liolopliuva georgiana, Quoy and Gaim. Plaxiphora 

 costata, Blain., is replaced by Plaxiphora albida, Blain.; 

 Lucilina delecta, Thiele, either is replaced by Tonicia trun- 

 cata, Sow., or the record of the occurrence of that shell at 

 Broome, quoted in my paper (Trans. Roy. Soc. S. Austr., vol. 

 xliv., 1920, p. 291), collected by Dr. Mjoberg, must be altered 

 to Lucilinu delecta, Thiele. 



One other correction must be made. Dr. Torr (loc. cit., 

 p. 98) records the occurrence of Chiton exoptanda, Bednall, 

 on the strength of "one anterior valve and one median valve, 

 were taken from 20 fathoms in Geographe Bay." 



Through the kindness of Dr. Torr I have had the oppor- 

 tunity of examining these valves, and find that the anterior 

 valve has "eyes" and is possibly a worn valve of Lucilina 

 hulliana, Torr, and the median valve cannot be identified with 

 C. exoptanda ; the most that can be said is, that if the char- 

 acteristic sculptural features of that shell were ever present 

 they have been so worn off as to make determination impos- 

 sible. The colour approximates very closely to exoptanda. 



rXESCRIPTION OF PLATE VIII. 



Fig. 1. Rhyssoplax geralcltonensis, Ashby, xo£. 



}J 2a. Tonicia (Lucilina) delecta, Thiele, posterior valve, x6. 



,, 2b. ,, ,, ,,• ,, median valve, x6. 



,, 2c. ,, ,, ,, ,, anterior valve, x6. 



