vi PREFACE. 



Throughout the whole of the work Dr. Hudson has had the invaluable assistance 

 of Mr. Gosse's MS. notes, and of his close and constant revision of the proofs. 



The hearty thanks of the authors are due to Mr. Frank Crisp, one of the 

 secretaries of the Royal Microscopical Society, and editor of its Journal, for the 

 great service that he has rendered them by forwarding early notices of all the 

 pamphlets and papers published on the subject : anyone who is, or has been, 

 engaged in a task similar to this will know what time and labour have thus been 

 spared, by his thoughtful kindness. 



They are, too, greatly indebted to numerous kind correspondents for living 

 specimens, often obtained with no little expenditure of time and trouble, and for 

 the records of their observations on them ; as well as for valuable preparations 

 of rare species, which could not be sent alive : to these correspondents the 

 authors tender their grateful thanks. In each case where the specimen was new 

 or rare the name of the place in which it was found, and (when permitted) the 

 name also of the finder, has been added to the description. Thf,y wish, however, 

 to make special mention of how much they owe to Miss Saunders of Cheltenham, 

 Miss Davies of Woolston, Dr. F. Collins, and Mr. John Hood of Dundee, for their 

 constant kindness in sending a profuse number of specimens of many species, 

 some of which were of unusual interest. 



It is so natural to recommend one's own favourite pursuit that the recom- 

 mendation often carries but little weight ; and yet there is much to be said in 

 favour of the study of the Rotifera, that cannot be gainsaid. They are to be 

 found almost everywhere ; they cost nothing ; they require neither expensive 

 lenses nor an elaborate apparatus ; they tempt us to explore the country, and to 

 take pleasant walks ; they are beautiful themselves ; and they suggest all kinds 

 of difficult questions on life and being. Moreover there is happily still a great 

 store of scientific ignorance concerning them, thus leaving an ample field for 

 fresh discoveries. 



Nor is this all. The study of these animated specks (in which teeth, stomach, 

 muscles, and even a brain lie hidden in the compass of an invisible mote) irre- 

 sistibly leads the mind to the contemplation of Him, whose almighty hand is as 

 visible in an atom of this animated dust, as it is in the myriad sparkles of the 

 starlit heavens. 



C. T. II. 



