392 CAMBRIAN AND SILURIAN IN NORTH AMERICA. [XV. 



name of Barrandia, but finding this name preoccupied, suggested 

 in 1861, in the fourteenth Regents' Report, that of Olenellus, 

 which was subsequently adopted by Billings in 1865. (Palaeo- 

 zoic Fossils, pages 365, 419.) In 1860, Emmons, in his Manual 

 of Geology, described the same species, but placed them in the 

 genus Paradoxides, as P. Thompsoni and P. Vermontana. Hall 

 had already, in 1847, in the first volume of his Palaeontology 

 of New York, referred to Olenus the Elliptocephalus asaphoides 

 of Emmons, and also a fragment of another trilobite from 

 Saratoga Lake ; both of which were described as belonging to 

 the Hudson-River group of the New York system, or to a still 

 higher horizon. The reasons for this will appear in the sequel. 

 The JSlliptocephalus, with another trilobite named by Emmons 

 Atops (referred by Hall to Calymene, and subsequently by Bil- 

 lings to Conocwyphe), occurs at Greenwich, New York. These 

 were by Emmons, in his essay on the Taconic system (in 1 844), 

 described as characteristic. of that system of rocks. 



A copy of the Regents' Report for 1859 having been sent by 

 Billings to Barrande, this eminent palaeontologist, in a letter 

 addressed to Professor Bronn of Heidelberg, July 16, 1860 

 (American Journal of Science (2), XXXI. 212), called attention 

 to the trilobites therein figured, and declared that no palaeon- 

 tologist familiar with the trilobites of Scandinavia would " have 

 hesitated to class them among the species of the primordial 

 fauna, and to place the schists enclosing them in one of the 

 formations containing this fauna. Such is my profound convic- 

 tion," etc. The letter containing this statement had already 

 appeared in the American Journal of Science for March, 1861, 

 but Mr. Billings in his note just referred to, on the fossils of 

 Highgate, in the same Journal for September of that year, 

 makes no allusion to it. In March, 1862, however, he re- 

 turns to the subject of the sand-rock, in a more detailed commu- 

 nication (Ibid. (2), XXXIII. 100), and after correcting some 

 emissions in his former note, alludes in the following language 

 to Mr. Barrande, and to the expressed opinion of the latter, 

 just quoted, with regard to the fossils in question and the 

 rocks containing them : ' I must also state that Barrande first 



