feY W. N. BENSON. 32i 



the exact sequence of formations and tectonic structures devel- 

 oped. The present communication serves a twofold purpose 

 It completes the preliminary mapping of the serpentines of the 

 main line of intrusions from Warialda to Hanging Rock, a dis- 

 tance of over 130 miles; and secondly, it carries the detailed 

 tracing of the horizons determined in the Tamworth District 

 through into the Nundle District, permitting a more accurate 

 correlation of the several formations in the two districts than 

 was formerly possible, and thereby indicating that a much 

 greater complexity exists in the Nundle region than was assumed. 



Several features of interest occur in this district, which are 

 but barely represented beyond it. Firstly, there is the occur- 

 rence of the Loomberah Limestone, which runs throughout the 

 length of the district, and extends into the Nundle region. It 

 is an horizon absolutely distinct from that of the Nemingha or 

 Moore Creek Limestones, with a different lithology, and a different 

 and interesting fauna characterised by the presence of numerous 

 pentaraeroid shells, and a group of corals which do not occur in 

 the limestones of the two other horizons. In this, and in the 

 Nemingha limestones below are several species of Tryplasma^ 

 hitherto very rarely observed in the Devonian rocks of this 

 State,* while, in the latter, is a very rare feature, namely, the 

 occurrence of Foraminifera in Devonian rocks. 



Apart from the faunal peculiarities of this region, the devel- 

 opment of igneous rocks is of interest; there are here important 



■'■■ Other recorded occurrences of Tryplasma in Devonian rocks in New 

 South Wales are as folloMs : — 



1. An undescribed species found by Mr. Surveyor Campbell in the Parish 

 of Cuerindi, a few miles south-east of Manilla (Ann. Rep. Dept. of Mines, 

 1915, p. 189). 



2. T. lonsdalei var. 8calariformis, found by Cullen and the writer in 

 Nemingha Parish (This Series, Part v. Set Bibliography). 



3. An indefinite species in the Crawney Limestone, collected by Cullen 

 (Mem. Geol. Surv. N S. Wales, No. 13, p. 101). 



The second of these belongs to the horizon of the Nemingha Limestone. 

 The first and third are almost certainly on the Moore Creek Limestone 

 horizon. So that it has now been ascertained that Tryplasma may occur 

 in all three Middle Devonian Coral-limestones. 



