XV.] CAMBRIAN AND SILURIAN IN NORTH AMERICA. 405 



consin. It is by an error that Messrs. Harkness and Hicks, 

 in a recent paper (Quar. Geol. Jour., XXVII. 395), have as- 

 serted that Owen, in 1852, found there, together with these 

 genera, Conocephalus 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 hith- 

 erto wanting, a direct connecting link between the fauna of 

 the American Potsdam and the primordial zone of Bohemia. 



The history of the Paradoxides Harlani, alluded to by 

 Professor Hall, is as follows : in 1834, Dr. Jacob Green re- 

 ceived from Dr. Eichard Harlan the cast of a large trilobite 

 occurring in a silicious slate, which was in the collection of 

 Francis Alger of Boston, and, it was supposed, might have 

 come from Trenton Falls, New York. Dr. Green, who at once 

 pointed out the fact that the rock was wholly unlike any found 

 at this locality, declared the fossil to resemble greatly the Para- 

 doxides Tessini, Brongn., the former Entomolithus paradoxus 

 of Linnseus, from Westrogothia, and named the species P. 

 Harlani. (Amer. Jour. Sci. (1), XXV. 336.) In 1856, the 

 attention of Professor William B. Eogers was called to a local- 

 ity of organic remains in Braintree, on the border of Quincy, 

 Massachusetts, where, on examination, he at once recognized 

 the Paradoxides Harlani in a silicious slate similar to that of 

 the original specimen. This was announced by him in a com- 

 munication to the American Academy of Sciences (Proc., Vol. 

 III.), as a proof of the protozoic age of some of the rocks of east- 

 ern Massachusetts. Professor Eogers then called attention to 

 the fact that this genus of trilobites is characteristic of the pri- 

 mordial fauna, and noticed that Barrande had already remarked 

 that, from the casts of P. Harlani in the London School of 

 Mines and the British Museum (which had been made from the 

 original specimen, and distributed by Dr. Green), this species 

 appeared to be identical with P. spinosus from Skrey in Bohe- 

 mia. 



In 1858, Salter found in specimens sent to the Bristol 

 Institution in England, by Mr. Bennett of Newfoundland, 

 from the promontory between St. Mary's and Placentia Bays, 



