XV.] CAMBRIAN AND SILURIAN IN NORTH AMERICA. 411 



species of which, according to Dr. Dawson, belonged to a cal- 

 careous chambered foraminiferal organism similar in its nature 

 to much of the Stromatopora of the second, and the closely 

 related Coenostroma of the third fauna. All of these Dawson 

 shows to have strong affinities to Eozoon, which is represented 

 by E. Canadense of the Laurentian, and by similar forms in 

 the newer crystalline schists of Hastings, Ontario, as well as 

 by the E. Bavaricum of the upper crystalline schists of Bava- 

 ria. The succession of related foraminiferal organisms is fur- 

 ther seen in the Devonian limestones of Michigan, where occur 

 great masses like Stromatopora, which present, according to 

 Dawson, a structure intermediate between the Eozoon of the 

 Laurentian and the genera Parkeria and Loftusia of the Cre- 

 taceous and the Eocene. These details are taken from Dr. 

 Dawson's presidential address to the Natural History Society 

 of Montreal, in May, 1872, where he has announced some of 

 the results of his studies, yet in progress, on the earlier 

 foraminifera. 



In 1856 the late Professor Emmons described (Amer. Jour. 

 Sci. (2), XXII. 389), under the name of Palceotrochis, certain 

 forms regarded by him as organic, found in North Carolina in 

 a bed of auriferous quartzite, among rocks referred to his 

 Taconic system. Their organic nature has also been main- 

 tained by Professor Wurtz, but from my own examinations, I 

 agree with the opinion expressed by Professor Hall, and sub- 

 sequently supported by the observations of Professor Marsh 

 (Ibid. (2), XXIII. 278 ; XVL. 217), that the forms to which 

 the name of Palaeotrochis has been given are nothing more 

 * than silicious concretions. 



As regards the geological horizon of the series of strata to 

 which Sir William Logan has given the name of the Quebec 

 group, the Sillery and Lauzon divisions have as yet yielded to 

 the paleontologist only two species of Obolella and one of 

 Lingula. Our comparisons must therefore be based upon the 

 fauna of the Levis limestones and graptolitic shales, which 

 have already been compared with the Middle Cambrian of 

 Sedgwick by the combined labors of Billings and Salter. 



