62 DE. G. J. HINDE ON THE EA.DIOLAEIA IN THE [Feb. 1 899, 



are similarly filled with radiolaria which have been infiltrated by 

 very fine clayey sediment, which is not removable by acid, and they 

 are therefore less recognizable in microscopic sections, though they 

 are shown weathered out on the surface of the rock. In the tuff- 

 rock the radiolaria occur singly, scattered in the calcite which 

 cements them and the tuff-fragments together ; they retain their 

 structures equally as well as those in the siliceous limestones, and, 

 not being crowded, the details of their forms can be more readily 

 distinguished in microscopic sections. 



Fifty-three species, belonging to 29 genera, have been recognized ; 

 4 genera and all the species are regarded as new, nearly all are 

 included in the division of the Spumellaria, but a few primitive 

 examples are referable to the Nassellaria. The predominant 

 majority of the radiolaria are Sphaeroidal and Pruuoidal forms with 

 medullary tests and radial spines. There is a singular absence of 

 many Discoidal genera common in other fossil radiolarian faunas, 

 and likewise of forms of Cyrtoidea. 



The geological age of the radiolarian rocks is proved to be 

 Devonian by the occurrence, in the lower part of the Tamworth 

 series, of corals characteristic of this period. The radiolaria, 

 however, do not show any close affinity with those which have been 

 described from Devonian rocks in Europe, but in some positive and 

 negative characters they agree with those of Ordovician age from 

 the South of Scotland, Cornwall, and from Cabrieres in Languedoc. 



As a rule, no other organisms beyond a very few simple sponge- 

 spicules and some minute dentate plates of uncertain character 

 occur in the same rocks with the radiolaria, but on two or three 

 limited horizons fragments of Lepidodendron australe are present in 

 claystones and tuffs, together with radiolaria. 



In the coral-bearing limestones of the Tamworth section radio- 

 laria have not as yet been found. On the other hand, in the 

 radiolarian siliceous limestones no calcareous organisms have been 

 recognized, and thus the source of the limestone in these rocks 

 remains uncertain. 



The radiolarian deposits of New South Wales are by far the 

 most extensive of any hitherto known. For the formation of so 

 great a thickness of rock, composed principally of extremely fine 

 calcareous or clayey materials tilled with the remains of these 

 microscopic organisms, an enormous period of quiet sedimentation 

 must be conceded. The radiolarian claystones of Tamworth may 

 be compared with the recent red clays with radiolaria of the 

 Challenger Report, and the tuff-rocks with the same forms 

 sparsely scattered in them also find their parallel in the volcanic 

 fragmentary materials which were dredged up by the Challenger 

 from the depths of the Southern Ocean. 



In conclusion I wish to express my great obligations to my 

 friend, Mr. J. J. H. Teall, F.R.S., for his advice and assistance in 

 ascertaining the character of the tuff-rocks containing radiolaria. 



