2 A. M. EDWARDS ON FOSSIL DIATOMACE^l. 



the red shale that occurs in the sandstone elsewhere. Last 

 summer I examined the shaley sandstone at Arlington, or 

 between Arlington and Kearney, about two miles from 

 Newark, on the opposite or eastern side of the Passaic river, 

 where the clayey or shaley sandstone is intercalated in strata 

 with the ordinary red sandstone. In this clayey shale I found 

 the Diatomaceee occurring in spots of clay about one inch or less 

 across. The material was cleaned by washing in weak aqua 

 ammonia and subsequent boiling in acids. The species found 

 are as follows : — 



Achnanthes subsessilis, Blir. (Achnanthidium) coarctatum, A. B. 



Amphora ovalis, Ktz. 



Cocconeis placentula, Ehr. 



Epithemia iurgida, Ehr. 



Melosira v avians, Ag. 



Nitzschia (Hantzschia) amphioxys, Sm. 



Synedra ulna, Ehr. 



Achnanthes (Achnanthidium) coarctation, A. B., is the same as 

 Stauroneis constricta, Ehr., and should be called Achnanthes 

 constricta, Ehr. It was found in Chile and Mexico by Ehrenberg, 

 and published by him in the " Abh. Berl. Akad.," the reprint in 

 1843 being commonly known as the " America." I have seen 

 it only in this preparation from the Newark sandstone. The 

 above are all I have detected up to the present, but a con- 

 sideration of how the shale originated warrants me in the 

 conclusion that other forms will be discovered when this sand- 

 stone is searched more thoroughly, and at other places than 

 Arlington, N.J. 



I have found every year, for the last four or five, in a run- 

 ning brook which is fed by the trickling of water down the 

 sandstone, coming from the glacial drift above it, the following 

 diatoms : — Nitzschia spectabilis, Ehr., not N. spectabilis, W. S., and 

 which includes N. linearis, W. S., N. multifasciata, Ktz., and 

 Synedra spectabilis, Ehr. There is also present a sigmoid form, 

 which looks like Nitzschia sigmoidea, Ehr. (= Navicula sigmoidea, 

 Ehr., = Nitz. elongata, A. EL H., = Sigmatella Nitzschii, Ktz). I 

 enumerate these to show they are not the same as those found 

 in the Newark sandstone. 



Now I wish to point out the way in which I think the sand- 

 stone and shale were formed. There were shales and sandstones 



