524 PALAEONTOLOGY OF QUEENSLAND, 



becomes vesicular. I previously recorded this as a variety of the 

 American G. americanum,, Hall, but I think now that perhaps it 

 had better be entirely separated. 



C. australe seems to have been a varialile species as to its form. 

 The specimen originally figured was of much larger growth, and 

 probably represents the adult condition. 



Loc. and Horizon. Reid's Gap, near Townsville (G. Sweet, 

 Colin. Sweet, Melbourne). Mid. Devonian. 



Genus — A c t i n o c y s t i s, Lindstrom, 1882. 



(Ofvers. K. Vet.Akad. Handl., 1882, No. 3, p. 21.) 



ACTINOCYSTIS 1 TERRA-KEC;lNyE, SJXllOV. 



(PL XXXIX. figs. 1 and 2.) 



Sp. Ghar. — Corallum simple, large, cono-cylindrical. Outer zone 

 wide, composed of successive cycles of upwardly directed vesicles ; 

 inner zone with from sixty-five to seventy septa, much thickened 

 towards their distal ends by stereoplasma. Fossula apparently 

 existing on the ventral side and containing a counter-septum. 



Obs. — I am not aware that this genus has before been recognised 

 in Australian rocks. The genus is typically an Upper Silurian 

 one, but other Devonian forms have been published by Mr. F. 

 Freeh.* 



I have not been fortunate enough to see a perfect corallum, and 

 our best specimen so far as the internal structure is concerned is 

 rather distorted in shape. The demarcation between the two 

 zones is well marked, the outer or vesicular area diminishing 

 rapidly in size downwards, the peripheral vesicles being the 

 largest, and diminishing in size inwards. The septa extend to 

 the centre of the corallum without coalescing, and not only are 

 they thickened with stereoplasma, but the interseptal loculi 

 become filled up, producing a more or less solid mass. The largest 

 specimen is four and a quarter inches long, the width of the 



* Dames and Kayser's Pal. Abhandhmgen, 1886, Bd. iii., Heft 3, p. 107. 



