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are Mr. Pattison's own words: — "A heavy sea tore off the 

 big kelp ( Lannnaria) outside the reef and washed it up on 

 the beach. The chiton was amongst the kelp, on the beach, 

 and the sea lice had probably eaten the fish out." These 

 facts and the flat, fragile character of the shell, with its 

 green-brown, transparent, epidermal covering, suggest the 

 probability of its living on the stems of the kelp under which 

 it was found. While the discovery of the host plant of the 

 genus Stenochiton, as described in my monograph (Trans. 

 Roy. Soc. S. Austr., vol. xlii., 1918), has led to their dis- 

 covery in some of the other States, is it not quite feasible 

 that a similar search on the stems of some forms of algae 

 may reveal a race of Polyplacophora living thereon. 



Remarks. — This remarkable shell presents many unique 

 features, the extremely reduced area of the tegmentum, the 

 modified character of the sutural laminae, the exceptional 

 development of the insertion plates, the partial or entire 

 absence of slits, the transparent granula epidermal covering, 

 and the peculiar posterior lobing of the insertion plates, 

 widely separates this from any other known form in Aus- 

 tralian waters, and, I believe, no near ally has up to the 

 present been discovered in the Southern Hemisphere. Per- 

 haps the nearest relative in our southern seas is the New 

 Zealand shell, Cryptoconchus porosus, Burrow; but that 

 species cannot be said to be very closely allied, as it only 

 possesses a few characters in common. I have quoted the 

 original description of both genus and species as published by 

 Dr. Pilsbry in his famous Monograph. In the main my 

 description, which has been written without any special 

 reference to the earlier writers, will be found very closely to 

 correspond therewith, but there are some rather important 

 differences. In the first place, the sutural laminae are by no 

 means obsolete, as stated by Adams and Angas, and there is 

 considerably more overlapping of the valves than was noticed 

 by Carpenter, the laminae, in some valves, reaching fully two- 

 thirds across the tegmentum. The insertion plates are 

 abnormally developed ; in fact, this species seems to have 

 specialized in this form of development, and, in some measure, 

 adapted the character of the tail valve to the median valves. 

 The lateral insertion plates are joined behind the tegmentum 

 and produced, posteriorly, in two lobes with a sinus between 

 them, a feature that is present in a very modified form 

 in the tail valve of some of the Acanthochitons. While in 

 the undissected shell under examination I cannot detect any 

 slits in any of the insertion plates, I cannot say that they do 

 not exist in a modified form. The interior of the tail valve is 

 radially grooved and scored, until the girdle is approached, 



