BARRANDE'S VIEWS. 377 



ON THE PRIMORDIAL FAUNA AND THE TACONIO SYSTEM OF EMMONS, IN A 

 LETTER TO PROF. BRONN, OF HEIDELBERG. * 



" Paris, July, 16, 1860. 



ee % 9 I i iave recently received thanks to the kindness of Mr. E. Billings, the learned palaeontolo- 

 gist of the Geological Survey of Canada a very interesting pamphlet entitled ' Twelfth Annual Report of 

 the Regents of the University of the State of New York, 1859.' If you possess this publication, you 

 will find there, at page 59, a memoir of Prof. J. Hall, entitled ' Trilohites of the Shales of the Hudson 

 River Group.' This savant there describes three species under the names Olenus Thompsoni, Olenus Ver- 

 montana, and Pdtura (Olenus) holopyga. The well-defined characters of these trilobites are des- 

 cribed with the clearness and precision to be expected from so skillful and experienced a palaeontologist as 

 James Hall. 



" Although the specimens are incomplete, their primordial nature cannot admit of the least doubt, when 

 the descriptions are read, accompanied with wood engravings which the large dimensions of these three species 

 render sufficiently exact, The first is 105 millim. long by 80 broad, the other two are somewhat smaller. 



" The heads of the two Oleni being deteriorated, the furrows of the glabella cannot be recognized. The 

 thorax has a common and remarkable character, which consists in the greater development of the third 

 segment, the point of which is stronger and longer than in all the other pleura. This is a striking resemblance 

 to the Paradoxides, the second segment of which has the same peculiarity. Besides, there is an intimate 

 relation between these two primordial types, and we should not be surprised if America furnished us with 

 forms uniting most of their characteristics. The pygidium of 0. Thompsoni, the only one that is* known, 

 shows no segmentation, and attests by its exiguity its relation to a primordial trilobite. P. holopyga, by its 

 whole appearance, resembles the species of Sweden so well known by the name of P. Scarabceoides. 



" Thus all the characters of these three trilobites, as they are recognized and described by J. Hall, are 

 those of the trilobites of the primordial fauna of Europe. This is so true, that I think I may say without 

 fear, if M. Angelin, or any other palaeontologist practiced in distinguishing the trilobites of Scandinavia, 

 had met with these three American forms in Sweden or Norway, he would not have hesitated to class them 

 among the species of the Primordial fauna, and to place the schists inclosing them in one of the formations 

 containing this fauna. Such is my profound conviction, and I think any one who has made a serious study 

 of the trilobitic forms and of their vertical distribution in the oldest formations will be of the same opinion. 



" Besides, all who have seriously studied paleontology know well that each geological epoch, or each 

 fauna, has its proper and characteristic forms, which once extinct re-appear no more. This is one of the 

 great and beautiful results of your immense researches, which have generalized this law, recognized by 

 each one of us within the limits of the strata he describes. 



"The great American paleontologist arrived long since at the same conclusion, for in 1847 he wrote 

 the following passage in the Introduction to the first volume of the Monumental Work consecrated to the 

 Palaeontology of New York. 



" ' Every step in this research tends to convince us that the succession of strata, when clearly shown, 

 furnishes conclusive proofs of the existence of a regular sequence among the earlier organisms. We are 

 more and more able, as we advance, to observe that the Author of nature, though always working upon the 

 same plan and producing an infinite variety of forms almost incomprehensible to us, has never repeated the 

 same forms in successive creations. The various organisms called into existence have performed their parts 

 in the economy of creation, have lived their period and perished. This we find to be as true among the 

 simple and less conspicuous forms of the paleozoic series, as in the more remarkable fauna of later periods.' 

 J. Hall, Pal. of New York, Vol. I, p. 23. 



" When an eminent man expresses such ideas so eloquently, it is because they rise from his deepest con- 

 victions. It must then be conceived that J. Hall, restrained by the artificial combinations of stratigraphy 

 previously adopted by him, has done violence to his pala3ontological doctrines, when, seeing before him the 



* Proceed. Boston S. N. Hist, vol. vii, Dec., 1860, p. 371. 



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