horn expedition — paleontology. 113 



Class Ectiinodermata. 



Tlio separate joints of sloudor crinoid stems are not infrequent on tlie surfaces 

 of tlie limestones in Middle Valle)^, and have also heen observed in the same beds 

 on the north side of George Gill Range. The fragment of stem ligiired (Fig. 21a) 

 lias a diameter of tin-ee mm., and consists of twenty-three joints in a length of 

 eight mm. An articular face is shown in Fig. 27/'. 



Class Zoantiiaria. 



Two species of corals occur in the limestones at Middle Valley and George 

 Gill Range. One consists of a cylindrical stem with simple forked liranches ; the 

 other forms explanulate tliin crusts. They may lielong to Cluelilcs, hut the con- 

 dition of the specimens does not permit of microscopic analysis, and thei-efore the 

 generic position is indeterminable. 



Class Spongida. 



The presence of sponge-rootlets in the Larapintine siliceous beds has ali-eady 

 been recorded by Mr. Howchin (iv.). Moreover, the (juartzite at Finke Goi-ge is 

 penetrated through a vei'tical thickness of four inches Ijy cylindrical casts of aliout 

 1'5 mm. in diameter; and though the casts are larger ^vxn Hyalostelia I'oils usually 

 are, yet it is more probable that they are so tlian annelide burrows. 



4. Correlation. 



By the presence of Endoceras and Asaphiis, as well as by the affinities of 

 many of the Molluscan species, it may .safely be concluded that the fauna is 

 Ordovician ; whilst the remarkal)le preponderance of Isoarar imparts a local 

 featuie. Hitherto the only known Ordovician f.auiia in Continental Austi-alia 

 is that of the auriferous graptolite slates of Victoria ; Ijut that fauna is almost 

 entirely composed of Giaptolites, and is not in any way comparable with that of 

 llie Larapintine rocks. Diligent search was made for Graptolites in the large 

 development of argillaceous I)eds towards the base of tlio Larapintine Series in 

 Stokes Pass, but without success. 



The question naturally arises, are the Larapintine beds and the Victorian 

 graptolite slates contemporaneous, or, if not, what is their relative position? The 

 answer is supplied l)y the sequence of the faunas in the Ordovician .Systi'm in 

 Tasmania. 



