Palaeozoic Geology oj Victoria. 83 



Class Brachiopoda 

 Lingulella 



Orthis (Plectorthis) platystrophioides. 

 (Originally confused with Platystrophia biforata.) 

 Class Gasteropoda. 



Scenella t^nuistriata, Chapman. 



Related to Stenotheca — Cambrian of South Australia. 

 Class Crustacea, Sub. Class Trilobita. 



Agnostus australiensis, Chapman. 



Ptychoparia thielei, Chapman. 



Ptychoparia minima, Chapman. 



Crepicephalus etheridgei, Chapman. 



The liniestone has a pleasing grey colour, is crystalline, and,, 

 when polished, would make an attractive ornamental stone, but in 

 its present inaccessible position there is no immediate prospect of 

 it being available for use. No quantitative analysis of its compo- 

 sition has been made, but a qualitative test sbowed that it was 

 relatively pure, with only a small percentage of magnesium car- 

 bonate. All the outcrops are of lenticular character and small 

 extent, the two largest being No. 1 Dolodrook, and that at Roan 

 Horse Gully. The latter can be traced along the strike for about 

 thre-e hundred yards, and shows a good face towards Roan Horse 

 Gully of about a chain in width. 



Upper Ordovician. — These rocks, consisting of hlack slates, with 

 highly cherty bands frequently intensely contorted, have been re- 

 ferred to in a previous paper (13), but their extent and relation- 

 ship to the other rocks in the vicinity had not been fully traced. 

 It had been recognised in general that they wrapped round the 

 central inlier of Serpentine and associated rocks, but the outer 

 boundary had not been followed. The result of additional field 

 work makes it now possible to indicate these features on the map 

 presented; showing that the Ordovician rocks are in turn enveloped 

 by an outer ring of later sediments, with a distinct lithological 

 and palaeontological break. The slates are everywhere readily dis- 

 tinguished in the field from the less indurated shales and sandstones 

 of the next series. Graptrdites are abundant throughout even in 

 the most highly cherty representatives, but naturally the best pre- 

 served specimens are obtained from the less altered bands. The 

 forms represented are uniformly Upper Ordovician types. The first 

 graptolites were obtained by the writer in 1905, and wore described 

 by the late Dr. T. S. Hall (1 4). Since then other forms have been 



