432 THE CANADIAN NATURALIST. [Vol. Vl. 



he extended this observation to the Calciferous and Chazy, both 

 of which he placed below this horizon ; which until a year or 

 two previous had been looked upon as the base of the paleozoic 

 series in Great Britain, and was subsequently made the lower 

 limit of the second fauna of Barrande. Although from these 

 facts it was probable that these lower members of the New York 

 system might correspond to the primordial fjiuna of Barrande, 

 we still remained, in the lano;uao;e of Prof. Hall, without " the 

 means of parallelizing our formations with those of Bohemia, by 

 the f\iuna there known. The nearest approach to the type of 

 the primordial trilobites was found in the Potsdam of the north- 

 west, described by Dr. D. D. Owen ; but none of these had been 

 generically identified with Bohemian forms, and the prevailing 

 opinion, sanctioned as I have understood, by Mr. Barrande, was 

 that the primordial fauna had not been discovered in this country 

 until the re-discovery (in 1856) of Paradoxides Harlani at 

 Braintree, Mass. The fragmentary fossils published in vol. I of 

 the Paleontology of New York, and similar forms of the so-called 

 Taconic system, were justly regarded as insufficient to warrant 

 any conclusions." [Amer. Jour. Sci. II. xxxi, 225]. Such, accord- 

 ing to Prof Hall, was the state of the question up to 1860. The 

 Conocephalus, detected by him from the red sandrock of Ver- 

 mont, in 1847, and subsequently recognized in Europe as an 

 exclusively primordial type, seems to have been forgotten by 

 Hall, and overlooked by others, until it was re-discovered in the 

 sandrock by Billings in 1861. He had previously, in 1860, 

 detected the same genus at Point Levis, together with Ario- 

 nellus, and other purely primordial types. Associated with these, 

 and with many other trilobites belonging to the second fauna, 

 were found several species of Dikellocephalus and Menocephalus, 

 genera first made known by Owen from the Potsdam of Wiscon- 

 sin. It is by an error that Messrs, Harkness and Hicks, in a 

 recent paper [Quar. Geol. Jour., xxvii, 395] have asserted that 

 Owen, in 1852, found there, together with these genera, Conoce- 

 phalus and Arionellus ; the history of the first discovery of these 

 genera in America, being as above given. The limestones of 

 Point Levis thus furnished what was hitherto wanting, a direct 

 connectino; link between the fauna of the American Potsdam and 

 the primordial zone of Bohemia. 



The history of the Faradoxldes Harlani, alluded to by Prof. 

 Hall, is as follows: In 1834, Dr. Jacob Green received from Dr, 



