176 E. M. Kindle — Diatomaceous Dust. 



ber 2, 1907, and covered an extensive area in northwestern 

 Alaska, including the greater part of the Seward Peninsula. 

 Samples of the gray dust show very fine-textured earthy 

 material of about the same degree of coarseness as is seen 

 ordinarily in the loess. 



An interesting feature of these samples of ice-borne dust is 

 the presence in most of them of considerable numbers of 

 marine diatoms. These organisms are quite as abundant in the 

 dust sample which is chiefly of volcanic origin as in the gray 

 non-volcanic dust. Through the kindness of Dr. Albert 

 Mann, the writer is able to present a list of the species which 

 w T ere found in the samples collected. These were obtained 

 from the ice floes about 30 miles northwest of Cape Romanzof. 



The list which follows gives the species which w T ere recog- 

 nized by Dr. Mann : 



List of Diatoms from Ice Floes ; by Albert Mann. 



" I find the dust collected on ice-floes in Bering Sea to be fairly 

 rich in diatoms. Below are the species found therein : 



Goscinodiscus radiatus Elirenb. 



Coscinodiscus subtitis Ehrenb. 



Goscinodiscus curvatulus Grun. 



Coscinodiscus excentricus Ehrenb. 



Goscinodiscus lineatus Ehrenb. 



Goscinodiscus robustus Grew 



Goscinodiscus spec ? 



Goscinodiscus pustulatus Mann. 

 Biddulphia aurita (Lung.) Breb. & God. 

 Melosira sulcata (Ehrwnb.) Kutz. 

 Actinoptychus undulatus 

 JVavicula brasiliensis Grun. 

 JVa v icula font in a lis Grun. 



Coscinodiscus apiculatus Ehrenb. 



Gyrosigma thuringicum (K.) Bab. See Wm. 

 Smith's Synop. Brit. Diatoms; Yol. I; Pi. 21 ; 

 Fig. 205 ; p. 65. Mann, Diat. Albatross Voyages: 

 p. 366. 



" This last species should retain its well known name 

 Pleurosigma angulatum W. Sm. 



" The first named species, C. Radiatus, is by far the most 

 common. It may be of interest to note that the above species 

 were found by me in the dredgings of the S. S. Albatross, 

 made in the southern part of Bering Sea, mostly at consider- 

 able depths. The new species, O. Pustulatus, Mann, was 

 found at a depth of over 1800 fathoms. 



" Coscinodiscus spec? is an unnamed species. I found this 

 also in the Bering Sea dredgings and mentioned it in my 



