vi PREFACE. 



requisite knowledge. In either case, the necessary thing is an 

 acquaintance with the complex structure and the life-history of 

 both the higher animals we meet upon the farm, which may 

 serve as host, and also of the smaller organisms met along with 

 them, whether injurious or beneficial, parasitic or leading an 

 independent existence. With an injurious insect, for example, 

 there is some period when it is open to attack : our observation 

 should enable us to discover this period, and our science to 

 suggest an appropriate weapon. In the same way our domestic 

 animals are weak at certain points and at certain times : only 

 an intimate knowledge of their organisation and their habits 

 will enable us to apply the corresponding safeguards. 



In the following text-book the writer has endeavoured to 

 summarise the habits, characters, and development of the 

 animals that may be met with in farm and garden. Groups pos- 

 sessing little or no economic importance have been but briefly 

 referred to, such as the Ccelenterates, Sponges, and Echino- 

 derms. On the other hand, the structure of one domestic 

 animal, the horse, has been treated at some length. 



It is hoped that the book may be of service to the farmer ; 

 but it is primarily written for the rapidly increasing class of 

 students in our Agricultural Colleges, &c. In their hands lies 

 the future of scientific agriculture, in the development of which 

 economic zoology must play not perhaps the least part. 



My thanks must here be expressed to Sir George Brown, 

 K.C.B., for kindly revising the chapter on the Anatomy of the 

 Horse, and for other help generally ; to Dr Hans Gadow for 

 the great trouble he has taken in examining the proof-sheets of 

 chapters xiv., xv., and xvi., and for his valuable advice in other 

 matters. The chapters on ]\Iites and Insects have been read 

 over by Mr Charles Whitehead; and to him I tender my grateful 

 thanks, not only for his help in examining the proofs, but also 

 for allowing me the use of some of his excellent figures from 

 the publications of the Board of Agriculture. In connection 

 with the latter, I must here acknowledge the courteous per- 



