of the Island of Tasmania. 153 



limestones.* They are, in some cases, slightly argillaceous and 

 thickly bedded, but ordinarily compact and massive. They are 

 jointed in a variety of directions, and the fissures have been 

 filled with calcareous spars. Irregular fissures or veins of 

 calcareous spars and quartz ramify through the formation. 

 These vary in thickness, and contain galena. These lime- 

 stones appear a^ain at the great bend of the Gordon River, 

 and at Point Hibbs on the West Coast, at the junction of 

 the Franklin and Gordon. They are then succeeded 

 by sandstones and grits. Below these is a coarse con- 

 glomerate consisting of quartz pebbles in a siliceous cement, 

 succeeded by siliceous grits and a variety of sandstones, 

 micaceous sandstones, purple grits, and streaked with 

 quartz veins, apparently passing down into clay, slate, 

 quartzite and micaceous schists. The conglomerate forms 

 the most conspicuous summits of the ranges west of the 

 King's River. Steel grey and yellow clay slates, with 

 fossils, are found in the Mersey district. The organisms 

 include Phacops and Ogygia, Calymene Conocephalites, 

 Orthis Euomphalus.*f" Messrs. Etheridge, Lesquereux, and 

 Dana have considered the fossils as indicating one of the 

 Lower Silurian formations. Similar formations, but of 

 undetermined age, have been received from Fingal. 



The following Lower Silurian fossils have been recorded 

 from Western Tasmania : — Retzia minima, Cyrtodonta 

 auriculata, C. compressa, C. distorta, C. gibhulosa, C. inflata, 

 C. obliquata, 0. pinguis, C. re versa. J Tellinomya amyg- 

 dala, T. antipoda, Bellerophon pugnus, Eunema gemula, 

 Helicotoma Milligani, H. pusilla, Holopsea munica, Hor- 

 motoma nerinsea, H. usitata, Murchisonia Franklinii, M. 

 mimetica, Raphistoma geterna, Scatites australis, Troch- 

 onema, Bigsbyana, Lituites Gouldii, Orthoceras, antilope, 

 P. Murchisoni, P. theca, C. Youngii. There is no Upper 

 Silurian fossil recorded from Tasmania. 



Silurian strata, but without fossils, were reported by Mr. 

 Charles Gould (at one time Government geologist) from the 

 north-eastern part of the island, in the county of Dorset. He 

 says it would be impossible to define the limits of these forma- 



* The Gordon limestones are most probably the equivalent of the Chud- 

 leigh and Midland Plains beds. .• 



j Proceeding s of the Royal Society of Victoria, for 1874, p. 27. 



% All these are quoted as MS. names of Salter in Bigsby's TJiesatirug 

 Silurieus. 1868, p. 140. 



