228 C. D. WALCOTT FKE-CAMBRIAN FOSSILIFEROUS FORMATIONS 



Pdlasotrochis. — Since the first description of Palseotrochis as a coral, by 

 Professor E. Emmons in 1856, it has l^een frequently referred to as a 

 pre-Paleozoic fossil. At my request Mr J. S. Diller has made a study of 

 the form, and he fully corroborates Professor J. A. Holmes' view that 

 Palseotrochis is of inorganic origin and occurs in an acid volcanic rock. 

 As his notes contain much that is of interest, he kindly prepared the 

 following abstract : 



" Professor Ebenezer Emmons in 1856 figured and described * from the ' Taconic ' 

 rocks of North Carolina a number of more or less retrularly striated, biconical forms, 

 to which he gave the names Palxotrochis major and Palseotrochis minor , and regarded 

 them not only as silicious corals, but also the oldest representatives of animal life 

 upon the globe. Professor James Hall f regarded them as concretions, and Pro- 

 fessor 0. C. Marsh J compared them to cone-in-cone. Mr C. H. White, § who 

 strongly advocates the organic nature of Palseotrochis, has published a fuller account 

 of its form and structure. 



" Professor J. A. Holmes, State Geologist of North Carolina, in 1887 visited the 

 Sam Christian gold mine and studied the Pal^eotrochis-bearing rock in the field. 

 He considered the rock of igneous origin, and in this view he has the support of 

 Messrs H. B. C. Nitze and George B. Hanna, who suggest || that the rocks are 

 silicious volcanics, and that at least some of the silicious pebbly concretions are 

 spherulites. 



"The specimens which, at the request of Mr Walcott, I had an opportunity to 

 study consist of three fragments about nine inches in diameter, sent by Professor 

 J. A. Holmes, who collected them in 1887 at the Sam Christian gold mine. Besides 

 these, there are from the same place several dozens of the original specimens of 

 Palpeotrochis collected by Professor Emmons. Specimens of the rock and isolated 

 fossils have been cut and polished and thin-sections prepared for microscopical 

 study.. 



" The rock which contains Palyeotrochis is full of nodules of various shapes and 

 sizes, ranging from that of a pin's head to nearly two inches in diameter. These 

 are the supjiosed concretions and fossils, and many of them have a radial fibrous 

 structure which under the influence of the weather becomes white like kaolin. A 

 careful study of the nodules in the hand specimen tends to convince one that how- 

 ever difierent in form and size they may appear, all belong to one series and have 

 essentially the same origin. 



"A microscopical study of thin-sections of the rock reveals the fact that the 

 nodules are spherulites, a common feature in acid volcanic rocks. They are com- 

 posed in most cases chiefly of fibrous feldspar, with quartz or tridymite. Although 

 the fibers are too fine for optical determination, microscopical tests show^ them to 

 be feldspar rich in sodium and potassium. The feldspar is probably anorthoclase. 

 The biconical forms which have been called Palseotrochis are generally composed 



* Geological Report of the midland counties of Nortli Carolina, p. 02 ; also km. Jour. Sol., 2d ser., 

 vol. xxii, p. 39, aud vol. xxiv, p. 151. 



t Am. Jour. Sci., 2d ser., vol. xxiii, p. 278. 



t Ibid., vol. xlv, p. 218. 



g Journal of the Elisha Mitchell Scientific Society, Chapel Hill, North Carolina, part 2, July to 

 December, 1894, pp. 50-06. 



II North Carolina Geological Survey, Bull. no. 3, pp. 37 and 39. 



