BY W. S. DUN, W. H. RANDS, AND PROFESSOR DAVID. 303 



and (juartz, on which discordantly rests a narrow band of soft 

 ochre-like clay, followed above by the white radiolarian rock, 

 which varies in places from 10 to 30 feet in thickness. It is 

 covered by a layer of ironstone conglomerate, of a few feet in 

 thickness, which caps the cliff. The white rock appears to be 

 nearly horizontal; it contains, more particularl}'- in the upper 

 portion, numerous nodules, var3dng in size from that of a walnut 

 to that of a cocoanut. In weathering it becomes soft and shows 

 a great variety of tints, from pure white to deep red. No fossils 

 can be found in it. It is used extensively for building purposes, 

 and it is eaten by the natives, probably on account of its purgative 

 properties. Mr. Bassett-Smith further states that the white 

 radiolarian rock is unaffected by heated hydrochloric or nitric 

 acid, and it is the same as that designated 'magnesite' in Tenison- 

 Wood's report. It thus seems probable that this material, so 

 widely distributed in the northern area of Australia, and reaching 

 in places a thickness of 130 feet, may prove to be, as already 

 suggested, a deep-sea deposit of radiolarian origin." 



The forms described belong to the suborders Prunoidea, Dis- 

 coidea, and Cyrtoidea, and comprise the following genera and 

 species : — 



Prunoidea — Cenellipsis. 

 DiscoiDEA — Astrophacus, spp. a. <3& b. 

 Lithocyclia exilis. 

 A^iiphihrachium crassum. 



,, triincat'itm. 



fragile. 

 sp. 

 Spongodisciis expansus. 

 spp. 

 Spongolena symmetrica. 

 Cyrtoidea — Dictyomitra australis. 



,, triangularis. 



Lithocampe fusiformis. 

 Stichocapsa pinguis. 

 ,, chrysalis. 



