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II. — Fifth List of New Rotifers since 1889, 

 {Period 1912-1915.) 



By Charles F. Eousselet, F.R.M.S. 



{Read December 15, 1915.) 



In the four previous Lists of New Eotifers since 1889 published in 

 this Journal* since 1893, I have recorded a total of 607 names. 

 The present Fifth List contains 132 additional species described 

 since 1912, making a total of 739 since 1889, the date of issue of 

 the Supplement to Hudson and Gosse's great Monograph. 



In 1889 Dr. Hudson estimated the number of recognizable 

 species at about 400. 



In 1912, after making allowance for the numerous synonyms 

 and duplication of names, my estinlation of the Rotiferous popula- 

 tion of the world was 850 ; at the end of 1915, after a similar 

 allowance, my estimate must be increased to approximately 960 

 species. 



With a few exceptions authors have of late years paid more 

 attention to adequate descriptions and correct figures of new species, 

 but there is still room for taking seriously to heart James Murray's 

 advice in one of his latest papers (249)t where he says : " The con- 

 scientious systematist, if he wishes his work to have any value, has 

 no alternative but to figure most of the species observed ; you 

 know then what he means by his names, and if he makes a mis- 

 identification, no harm is done"; and again ('J53) : "If a man 

 can neither observe carefully, nor describe faithfully, nor draw 

 accurately, surely he might leave the poor beasts alone." Few 

 persons, I take it, will be found to disagree with these recom- 

 mendations. 



James Murray has unfortunately not returned from his last 

 journey with the Canadian Arctic Expedition under Stefansson. 

 The ' Karluk,' on which he served as Oceanographer and Biologist 

 of the Expedition, was crushed in the ice and sank near Herald 

 Island, and though a few succeeded in making their escape to 



* For the four previous Lists, see thiis Journal, 1893, pp. 450-458; 1897, 

 pp. 10-15 ; 1902, pp. 148-154 ; 1912, pp. 151-165. 



t The numbers in brackets refer to the Bibliography at the end of the paper. 



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