[Proc. Roy. Son. Victoria, 30 (N.S.), Pt. H., 1918]. 



Art. XIII. — Oil the Occurrence of Acrotreta in Lower 

 Palaeozoic ( Lancefieldian and Heathcotian) Shales in 

 Victoria. 



By FREDERICK CHAPMAN, A.L.S., «tc. 

 (Palaeontologist, National Museum, Melbourne). 



(With Plate XXVI.). 



[Read 8th November, 1917]. 



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General Remarks. 



The specimens forming the basis of the present paper come from 

 two sources. 



(1) The better preserved specimens, dorsal and ventral valves, 

 were found by Professor Skeats, D.Sc, in a road-metal heap E. 

 of Mount William railway station and N.E. of Lancefield. The 

 matrix is a whitish or pale ashen grey siliceous shale, with obscure 

 crustacean remains (cf. Hymenocaris). In thin sections under a 

 high power, small cruciform spicules can be distinguished, prob- 

 ably referable to Protosporigia. 



(2) A smaller and slightly crushed and distorted interior of a 

 dorsal valve, apparently belonging to the same species, was found 

 by the late Dr. T. S. Hall, M.A., near Lancefield, which he pre- 

 sented to the Museum in 1908. 



When first examining Prof. Skeats' specimens, I was struck with 

 their resemblance to certain Cambrian brachiopods formerly placed 

 in the genus Linnarssonia by C. D. Walcott, which genus has since 

 been merged into Acrotreta, Kutorga. Acrotreta is a genus of 

 more or less cone-shaped brachiopods in which the pedicle opening 

 is simple, circular and apical on the central valve. The false car- 

 dinal area is apparent in the cast of the ventral valve in one of the 

 present specimens. 



Acrotreta antipodum, sp. nov. (Plate XXVI.) 



Description. — Valves wider than long, subovate in outline; pos- 

 terior obtuse to depressed, with a false cardinal area. Ventral 

 valve moderately high ; pedicle opening situated about one-fifth 

 from the posterior margin, apex concavely sloping to the posterior, 



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