DIATOMS FROM MURRAY ISLAND, AUSTRALIA. 



By Albert Mann. 



Of 7 samples submitted, the 5 examined by Dr. Cushman were destitute 

 of diatoms. Of the 2 fresh samples, that from line I, 200 feet, contained an 

 occasional diatom, but may be said to be practically without these organisms. 

 The sample from line I, 600 feet, was also exceedingly poor in the number of 

 diatoms, but contained a relatively large number of species, as follows: 



Navicula lyra Ehr. var. elliptica V. H. A. pellucida Greg. 



N. suborbicularis Lag. Coscinodiscus elegans Grev. 



M. aestiva Donk. Cocconeis scutellum Ehr. 



N. aspera (Ehr.) Kg. Pleurosigma strigosum W. S. var. 



N. sp. ? (perhaps wide var. N. arenaria). Melosira sulcata (Ehr.) Kg. 



Amphiprora maxima Greg. Cymbella scotica W. S. 



Amphora ovalis Kg. Climacosphenia moniligera Ehr. 



A. ventricosa Greg. 



Few if any of these forms were deficient in silica, unless it was the 

 Pleurosigma; but it is significant that this collection has a comparatively 

 large number of species of marine diatoms and yet an extreme poverty in 

 the quantity of these organisms. This indicates to me that the locality in 

 which they were collected was abundantly supplied with individuals of var- 

 ious species, fitted to multiply and inhabit these waters, and probably more 

 or less introduced from other localities, but that for some reason none of these 

 increased to any great extent. Therefore, with an exceedingly varied flora 

 of the diatoms we have an unusually scanty quantity of these organisms. 

 Had there been only one or two species found, this state of things might be 

 interpreted in a different way, but the great diversity of species and the great 

 poverty in numbers leave no explanation except that the waters of this 

 locality were unfitted for diatom development. 



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