PREFACE. 



THANKS are due to the following gentlemen, who have kindly 

 assisted the author by the loan or gift of specimens of Acari parasitic 

 on domestic animals, viz., Lieut.-Colonel A. Alcock, C.I.E., F.E.S., 

 of the London School of Tropical Medicine ; Professor J. H. Ash- 

 worth, D.Sc., F.R.S., Department of Zoology, University of Edin- 

 burgh ; G. A. H. Bedford, Esq., Veterinary Dept., Union of South 

 Africa ; F. C. Bishopp, Esq., United States Dept. of Agriculture ; 

 Professor 0. Charnock Bradley, M.D., D.Sc., M.E.V.C.S., Eoyal 

 (Dick) Veterinary College, Edinburgh ; Rev. G. H. Hewison, M.A. ; 

 Dr. M. Langeron, Laboratoire de Parasitologie, Faculte de Medecine, 

 Universite de Paris ; Professor R. G. Linton, M.R.C.V.S., Royal 

 (Dick) Veterinary College, Edinburgh ; Leslie Linzell, Esq., late of 

 the Royal Army Veterinary Corps ; Prof. A. Martin, Ecole Nationale 

 Veterinaire, Toulouse ; C. D. Soar, Esq. ; Prof. E. L. Trouessart, 

 Museum d'Histoire Naturelle, Paris. Also to Miss E. Knight, of the 

 Cancer Research Laboratory, Middlesex Hospital. 



The majority of the illustrations are reproductions of drawings 

 made by Mr. P. Highley and Mr. A. J. E. Terzi. These have been 

 drawn with great skill and care, and the thanks of the Trustees are 

 due to Mr. Hirst whose property they are for allowing them to be 

 used. Fig. 78 is from a photo by the Rev. G. H. Hewison, M.A. 

 Fig. 54 is reproduced by permission of Dr. Walter E. Collinge. 

 Figs. 62-66, 69 (a), 70, and 71 by permission of Dr. G. A. K. 

 Marshall, C.M.G. Figs. 40 and 79-83, by permission of Messrs. 

 Taylor and Francis. Figs. 1, 3, and 34 by permission of the 

 Quekett Microscopical Society. 



C. TATE REGAN, 



Keeper of Zooloyy. 



February, 1922. 



