CAMBRIAN GEOLOGY AND PALEONTOLOGY 



II 



No. 8.— THE SARDINIAN CAMBRIAN GENUS OLENOPSIS 



IN AMERICA 



By CHARLES D. WALCOTT 



(With Plate 36) 



INTRODUCTION 



The genus Olenopsis has received considerable attention from 

 authors who have written on the stratigraphy and paleontology of 

 the Cambrian strata of the Island of Sardinia, but up to the present 

 it has not been recognized in any Cambrian section where its strati- 

 graphic position in relation to the Olenellus and Paradoxides faunas 

 could be definitely determined. 



The presence of the genus in America has not been announced, 

 although a number of the cranidia of species referred to Ptychoparia 

 were very much like the cranidia of Olenopsis. 



The three species described in this paper give the genus a recog- 

 nized stratigraphic position over a wide area in North America, and 

 from this it is thought probable that the type species, Olenopsis 

 zoppii, occurs in the Cambrian series of Sardinia beneath the Middle 

 Cambrian Paradoxides beds, either in passage beds from the Lower 

 to the Middle Cambrian, or in the upper beds of the Lower 

 Cambrian. 



Dr. J. F. Pompeckj considered it probable that Olenopsis was 

 derived from Paradoxides^ but with our present information I am 

 inclined to consider that Olenopsis is more likely to be a form inter- 

 mediate between Holniia (restricted) and Paradoxides, or that the 

 two genera are descendent from the Holmia type of the Mesonacidae.* 

 We do not appear to have evidence that Olenopsis is stratigraphically 

 above Paradoxides. On the contrary it is below the horizon of the 

 Middle Cambrian in Pennsylvania and it is in the passage beds at 



^ ParadoxidesSinit von La Cabitza in Sardinien. Zeitschr. Deutschen 

 geol. Gesellsch., Bd. 53, Heft i, 1901, p. 19. 

 ^ Smithsonian Misc. Coll., Vol. 53, No. 6, 1910, pp. 253 and 254. 



Smithsonian Miscellaneous Collections, Vol. 57, No. 8. 



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