Mr. 11. Etiieridge on a Species o/* Terebratella. 21 



foui-teen feet in thickness, with great regularity. The whole 

 formation has much the appearance of chalk, containing both 

 "sand- pipes" and layers of black and white flints, and in 

 places is literally crammed with organic remains (Foramini- 

 fera, Entomostraca, Polyzoa, Echinoderms, and Mollusca), 

 some of the species of which are identical with existing forms, 

 whilst the whole bears a general resemblance to the fauna at 

 present living on the neighbouring coast. The Foraminifera 

 have been examined by Prof. T. Kupert Jones, F.R.S., and 

 Mr. W. K. Parker, F.R.S., who consider them to be probably 

 of Pliocene age and indicative of deep water ^. The Polyzoa 

 have also received attention at the hands of Prof. G. Busk, 

 F.E,.S. t, who considers it "probable that the formation in 

 which they are found corresponds in point of relation to the 

 existing state of things with the Lower Crag of England." 

 The general appearance of the strata indicates that the par- 

 ticles of which they are formed were deposited in a tranquil 

 sea, and derived from the destruction of coral reefs. This, 

 coralline limestone, or, as it is termed by Mr. Woods, the 

 " Crag," is estimated by the latter to occupy probably at least 

 one sixtli of the whole of Australia, but to attain its chief de- 

 velopment in that part of South Australia which extends from 

 the coast on the south northwards to the Murray River, west- 

 ward to the base of the Cape-Jervis range, whilst on the 

 east a ridge of trap-rocks, corresponding to the 141st meridian 

 of east longitude, along the limit of the colonies of Victoria 

 and South Australia, serves as a boundary in that direction. 

 This district, wholly occupied, with one or two trifling ex- 

 ceptions, by the coralline limestone or " Crag," contains an 

 area of 22,000 square miles. Near the Great Bend of the 

 Murray River the latter has cut its course through this forma- 

 tion, forming cliffs 150 feet high, from which Capt. Sturt, 

 the great explorer, collected fossils in about 140° E. longitude, 

 the majority of which are specifically identical, according to 

 Mr. Woods, with the Mount-Gambier fauna, whilst the re- 

 mainder are not found at the latter locality. Capt. Sturt 

 states that in 1845 he found similar fossils in a limestone 

 cropping out on both sides of Lake Torrens, whilst Mr. Woods 

 believes that the greater portion of Central Australia is occu- 

 pied by this deposit. In Victoria it is found still further east- 

 ward at Portland, underlying volcanic rocks, and extends 

 along the coast to between Port Fairy and Cape Otway. 

 Finally, in Tasmania beds have been described bearing a strong 

 resemblance to the Mount-Gambier Coralline Limestone. 



* Quart. Joiirn. Geol. Soc. 1860, xvi. p. 261. 

 t Ibid. p. 260, 



