G. D. Walcott — Position of the Olenellus Fauna. 387 



, The Olenellus Fauna. 



A summary of the Cambrian fauna is given in the Introduc- 

 tion to Bull. 30, U. S. Geol. Survey, in which the Olenellus 

 fauna is credited with 43 genera, 107 species and 2 varieties. 

 In this summary 3 genera and 19 species are included that are 

 not found in association with the genus Olenellus or typical 

 species of the fauna. They were found beneath the Potsdam 

 horizon and above the Georgia or Olenellus horizon, and are 

 now referred to the Middle Cambrian. They are : Proto- 

 spongia fenestrata Salter, Eocystitesff longidactylus Walcott, 

 Peperditia Argenta Walcott, Agnostus interstrictus White, 

 Olenoides JVevadensis Meek (sp.), 0. quadriceps Hall and 

 Whitfield (sp.), O. Wasatchensis Hall and Whitfield (sp.), 0. 

 spinosus Walcott, 0. typicalis Walcott, Ptyohoparia Housensis 

 Walcott, P. Kingi Meek (sp.), P. Piochensis Walcott, P. f 

 Prospectensis Walcott, P. guadrans Hall and Whitfield (sp.), 

 P. subcoronata Hall and Whitfield (sp.), Bathyuriscus How- 

 elli Walcott, B. productus Hall and Whitfield (sp.), and Asa- 

 phiscus Wheeleri Meek. Ptyohoparia Piochensis occurs 100 

 feet above the Olenellus zone proper, in the Highland Range 

 section,* but as it also occurs 1137 feet higher up in the same 

 section, it is now referred to the Middle Cambrian fauna and 

 not to the Olenellus fauna. 



From the Olenellus zone of eastern New York, I subse- 

 quently described :f Lingulella Granvillensis, Linnarssonia 

 Taconica, Orthis Saleme?isis, Hyolithellus micans, var. rugosa, 

 Modiolopsis f? prisca, Leperditia dermatoides, Aristozoa 

 rotundata, Microdiscus convexus, Olenoides Fordi, Soleno- 

 pleura ff tumida, Ptyohoparia Fitchi and P. f clavata, 

 and recent collections have added Agnostus desideratus, n. sp., 

 Agnostus of the type of A. pisiformis, and Zacanthoides 

 Eatoni n. sp. 



All of these occur in association with Olenellus, although 

 Linnarssonia Taconica, Agnostus desideratus, Agnostus type 

 of A. pisiformis. Microdiscus connexus, Zacanthoides Eatoni, 

 n. sp., are types of the Paradoxides fauna. 



Professor N. S. Shaler discovered an area of fossiliferous 

 Lower Cambrian rocks in Bristol County, Massachusetts, from 

 which he has described, in association with Mr. A. F. Foerste, 

 the following species \% Obolella crassa Hall (var.), Obolella ?, 

 Fordilla Troyensis Barrande % Lamellibranch ?, Scenella reti- 

 culata Billings, Stenotheca rugosa, var. pauper a, S. rugosa, 

 var. abrupta, S. recurvirostra (n. sp.), Platycevas primwuum 



* Bull. U. S. Geol. Survey, No. 30, 1886, pp. 33, 34. 

 f This Journal, III, vol. xxxiv, pp. 188-198, 1887. 

 % Bull. Mus. Comp. Zoology, vol. xvi, No. 2, 1888. 



Am. Jotje. Sci.— Third Series, Vol. XXXVII, No. 221.— May, 1889. 

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