PEEFACE 



THE Editors feel that they owe an apology and some explanation 

 to the readers of The Cambridge Natural History for the delay 

 which has occurred in the issue of this, the fourth in proper 

 order, but the last to appear of the ten volumes which compose 

 the work. The delay has been due principally to the untimely 

 death of Professor W. F. E. Weldon, who had undertaken to 

 write the Section on the Crustacea. The Chapter on the 

 Branchiopoda is all he actually left ready for publication, but it 

 gives an indication of the thorough way in which he had intended 

 to treat his subject. He had, however, superintended the 

 preparation of a number of beautiful illustrations, which show 

 that he had determined to use, in the main, first-hand knowledge. 

 Many of these figures have been incorporated in the article by 

 Mr. Geoffrey Smith, to whom the Editors wish to express their 

 thanks for taking up, almost at a moment's notice, the task which 

 had dropped from his teacher's hand. 



A further apology is due to the other contributors to this 

 volume. Their contributions have been in type for many years, 

 and owing to the inevitable delays indicated above they have been 

 called upon to make old articles new, ever an ungrateful labour. 



The appearance of this volume completes the work the Editors 

 embarked on some sixteen years ago. It coincides with the 

 cessation of an almost daily intercourse since the time when they 

 "came up" to Cambridge as freshmen in 1880. 



S. F. HARMER. 

 A. E. SHIPLEY. 



March 1909. 



