De Lautoue. — On a Diatoviaceous Deiiosit. 297 



became more abundant and prolific ; then, in order to fulfil 

 their functions in the balance of nature, the DiatomacecB also 

 increased in number and size ; and, finally, that, the con- 

 ditions being prepared for them, the higher forms of animal 

 life appeared and formed the limestone. 



Dr. G. Hartwig in " The Sea and its Living Wonders " says, 

 " "Without the diatoms there would be neither food for aquatic 

 animals nor (if it were possible for these to maintain them- 

 selves by preying on one another) could the ocean waters be 

 purified of the carbonic acid which animal respiration would be 

 continually imparting to it. Thus it is not in vain that they 

 abound in the n:iost inhospitable seas, where but for them no 

 sea-bird would flap its wings, and no dolphin dart through the 

 desert waters." 



Dr. Hartwig also states that they increase so quickly and 

 multiply by division (other authors say also by conjugation) 

 that in forty-eight hours a single diatom may multiply to 

 8,000,000, and in four days to 140,000,000,000,000, "when 

 the siliceous coverings of its enormous progeny will already 

 suffice to fill up a space of two cubic feet." (!) 



Many other remains found in these earths are highly in- 

 teresting, and no doubt are new to science. The Forammifera 

 are very abundant, especially in the calcareous deposits. I 

 have figured a few, Plate XX., fig. 6. The Eadiolaria and 

 PolycystincB are very striking and beautiful forms. As for the 

 spongioliths, they are so abundant and fine in Jackson's depo- 

 sit that Mr. B. W. Priest, an authority on the sponges, states 

 that for " size, variety, and quantity this deposit far surpasses 

 any previously discovered." Dr. Hind, I may add, is pre- 

 paring a monograph on the spongioliths of this locality. 



In examining the various deposits, and in working out 

 various details in connection with this paper, I have received 

 much assistance from Messrs. John Forrester and C. Peach, 

 of the Oamaru Harbour Board. Mr. Charles Gifford, of the 

 Waitaki High School, was, I believe, the first to find out and 

 examine the deposit in Jackson's paddock. Mr. Th. Isdaile, 

 of Enfield, has also given me much valuable information. 



With regard to the practical uses to which diatomaceous 

 earth may be applied, much, I imagine, depends upon its purity 

 and the relative quantity of silica which it contains. I regret 

 that I have been unable to get an analysis of this deposit, and 

 therefore cannot give the requisite information. The uses, 

 however, to w'hich diatom earth has been put are many and 

 important, and doubtless many others will be discovered in 

 the future. These, however, have been enumerated by Mr. 

 H. G. Hanks, State Mineralogist, California : — 



(1.) As a polishing-powder diatom earth has long been used 

 in the form of tripoli. As has been remarked, these almost 



