151 



the subject of the present communication to the Society. 

 They represent two localities and two horizons, geologically 

 speaking. The first and largest parcel, consisting almost 

 wholly of Trilobite remains, is from the Mersey River District, 

 North Tasmania, whilst the other fossils are from a Con- 

 glomerate of unknown age at Table Cape. It will perhaps be 

 best to consider the two as distinct from one another ; I shall 

 therefore describe them under separate headings. 



1. TRILOBITES AND OTHER FOSSILS FROM THE MERSEY RIVER 



DISTRICT. 



Plates 1 and 2. 



Mr. Stephens recorded the discovery of the beds " contain- 

 ing casts of Trilobites," as long ago as 1874, in a short verbal 

 notice on the subject.* It appears that a number of these 

 specimens were forwarded to Europe and Amei'ica through 

 the late Rev. W. B. Clarke, and casually examined by my 

 father and Professor L. Lesquereux. In the verbal notice 

 referred to, Mr. Stephens says, quoting from a letter received 

 from Mr. Clarke, " Both Mr, Etheridge and Mr. Les- 

 quereux had identified the genera Phacops, Ogygia, 

 Calymene, and Conocephalites, and considered the rock to be 

 the equivalent of the Potsdam Sandstone." 



Trilobites do not appear to have been found to any great 

 extent in the Palaeozoic rocks of Tasmania. Mr. Charles 

 Gould, some years ago, found impressions of them in the 

 rocks of the Mersey River District,t but I am not aware 

 that any description of these has appeared. In his remarks 

 on the Gordon Limestones, a set of beds probably distinct 

 from those now under consideration, Mr. Gould particularly 

 refers to the absence of Trilobites,^ although he speaks 

 of certain others, as the ^'Calymene beds of Tasmania." 



The matrix consists of a fine-grained, friable, and much 

 decomposed grit, in hand specimens of a bright ochreous 

 colour. The mass is almost exclusively composed of the 

 comminuted remains of Trilobites, in the form of casts, from 

 which the whole of the integument and external parts have 

 disappeared. Mr. Stephens writes me, " It is only in this one 

 spot in Tasmania that Trilobites have been found at all, 

 and here they are only obtainable from this friable jointy 

 matrix, which passes into a hard metamorphic sandstone with 

 brecciated bands, either barren of fossils or utterly refractory." 

 He adds, " I have named this formation the ' Caroline Creek 

 beds,' to prevent any mistake as to locality." 



The forms I have been able to distinguish amount to four 

 only, or perhaps five, and this has not been accomplished with- 

 out considerable difficulty, owing to the comminuted and 



■^ Papers and Proc. R. Soc. Tas, for 1874, p. 27. 

 t Fide Stephens, ibid for 1873, p. 38. J IMd 1866, p 27. 



