72 Scientific Intelligence . 



'3. Note on the paper in the November No. of this Journal on 

 (i A New Oriskany JBauna in Columbia Co., N I 7 ]," by S. T. 

 Barrett. (Communicated). — The paper entitled " Notice of a 

 New Oriskany Fauna in Columbia Co., N. Y., with List of Fos- 

 sils" by Messrs. Beecher and Clarke, containing occasional refer- 

 ences to rocks of similar horizon near Port Jervis, N. Y., seems 

 to me to remove much of the difficulty in the classification and 

 division, upon faunal grounds, of the rocks in this vicinity. 



If one includes the Dalmanites dentatus layer in the Lower 

 Helderberg group he finds himself confronted with the difficulty 

 amounting, I think, to an impossibility of running any dividing 

 line at all upon grounds of faunal relationship between that layer 

 and the strata lying above it and below the Cauda Galli Grit 

 and there is no Oriskany. 



The relations of the D. dentatus layer seem to be more with 

 the rocks above than those below it. Include it, and the 100 feet 

 of shale lying beluw it and above the Gray Limestone, No. 5, of 

 my paper,* with the 50 feet extending upwards above it to the 

 base of the Cauda Galli in the Oriskany group, and we have not 

 only easily found boundaries, but a thickness of about 150 feet 

 containing a fauna strongly individualized and peculiar. 



The Oriskany series, thus extended from Gray Limestone to 

 Cauda Galli, presents a fauna into which many Lower Helderberg 

 species persist along with characteristic Oriskany species, several 

 new to paleontology and others, according to Profs. Beecher and 

 Clarke, which originating in the Oriskany are continued up into 

 and reach a fuller stage of development in rocks of Lower De- 

 vonian age. 



Port Jervis, N. T., Dec. 1892. 



4. Subdivisions of the Azoic or Archaean in Northern Michi- 

 gan ; by M. E. Wadsworth. (Communicated.) — The work of 

 the Michigan Geological Survey in 1890 made it clear that the 

 Azoic System of i he Lake Superior district of Northern Michi- 

 gan was composed of at least three unconformable formations. 

 This conclusion was published by me early in 1891, in an article 

 entitled "A Sketch of the Geology of the Marquette and Ke- 

 weenawan Districts," which was appended to a pamphlet called 

 "Lake Superior along the South Shore." New York, 1891. 



These general conclusions have been confirmed by the work of 

 the two subsequent seasons, and two other unconformable forma- 

 tions rendered probable, although not yet proved conclusively. 

 A discussion of these points will stibsequently be given in detail 

 in the reports of the State Geologist. The following are the 

 formations as made out and named from prominent localities, by 

 the Michigan Survey, commencing with the oldest. 



There are given with this, the formations as determined by the 

 United States Geological Survey showing their supposed equiva- 

 lency. 



*This Journal, vol. xiii, p. B85, 1877. 



