^^^- 55'] FROM CHTPONS FARM, MULLION PARISH. 219' 



genus has only recently been constituted for some radiolaria in 

 the Devonian rocks of New South Wales,^ and it is interesting 

 to note that one of the Australian species is also represented at 

 Chypons, where it occurs probably on a lower geological horizon. 



No Cyrtoidal radiolaria have been recognized in the Cornwall 

 chert, and other organisms than radiolaria are apparently absent 

 in this rock. 



EXPLANATION OF PLATE XVI. 



[The specimens are from, the chert, of presumed Ordovician age, at Ohypons- 

 Farm, MuUion Parish (Cornwall). The slides containing the specimens belong 

 to Mr. Howard Fox, F.Gr.S., who intends to present them to the British 

 Museum (Natui-al History). All the figures are enlarged to the same scale of 

 200 diameters.] 



Fig. 1. Stigmosphcera echinata, sp. nov. Only the bases of the radial spines- 

 are preserved. 



2. Carposphcera nana, sp. nor. ■ 



3. Stigmosphcerostylus inceqtiaUs, sp. nov. The radial spines are im" 



perfect. 

 Figs. 4 & 5. Trochodiscus (?) duhms, sp. nov. 

 Fig. 6. Cenellipsis scihtla, sp. nov. 

 - 7. Cenellipsis setosa, sp. uov. 

 8. Cenellipsis favosa, sp. nov. 

 Figs. 9 & 10. Staurodritppa nucula, sp. nov. The radial spines are imperfect. 

 Fig. 11. Sta.urodriippa Foxii, sp. nov. The radial spines are all broken away ; 



the form is seen in section. 

 Figs. 12 & 13. 8taurodrupiKi Foxii. The specimens are seen in section ; the 

 radial spines are imperfect, and the fourth spine is wanting 

 in both examples. 

 Fig. 14. Druppalonche clavigera, gen. et sp. nov. Seen in section. 



15. Lruppalonche ovata, sp. nov. Seen in section ; the radial spines are 

 imperfect. 



Discussion. 



Dr. Hicks said that the additional evidence brought forward ia 

 this paper was most interesting, in its bearing on the phj^sical 

 conditions under which these chert-rocks were deposited. There 

 seemed to be no doubt that the area at the time was an oceanic oncy 

 and that the radiolaria lived there and were not drifted specimens. 

 He thought that the rocks were not older than, of Arenig age : but 

 it was unfortunate that other fossils, by which the age might be 

 satisfactorily determined, had not as yet been found. 



Mr. C. Eeid pointed out the exceptional importance of these 

 floating oceanic organisms for the correlation of rocks over widely 

 separated areas. He was glad to find that good specimens from 

 Mullion could now be described and figured. 



Dr. H. Woodward also spoke. 



The Author, in reply to Dr. Hicks, said that he had not touched 

 upon the question of age of the rock, since the evidence from the 

 radiolaria does not lead to any definite conclusions. There could 

 be no doubt that the radiolaria were in situ., for they would not 

 have retained their delicate structures if they had been exposed to 

 drifting at the sea-bottom. He thanked the Fellows for their 

 reception of his paper. 



1 Quart. Journ. Geoh Soc. vol. Iv (1899) p. 51. 



