324 



[46] 



APPENDIX II 



[Reprinted (with a few slight alterations) from Parasitology, Vol. IV, No. 1, 

 pp. 46-67, March, 1911.] 



ON THE ADAPTATION OF TICKS TO 

 THE HABITS OF THEIR HOSTS 1 . 



By GEORGE H. P. NUTTALL, F.R.S. 



In the course of the extended investigation upon ticks which we 

 have been conducting for some years, a very large number of specimens 

 have reached us from all parts of the world, thanks to the generous 

 aid which we have received from numerous collectors. In addition to 

 studying this material, the literature on ticks has been sifted for any 

 information which might throw light upon these parasites. A study of 

 the data relating to the structure and habits of ticks and of their host 

 relationships has brought to light certain facts which possess consider- 

 able interest and consequently appear to me worth recording in this 

 Journal. 



The superfamily Ixodoidea is divided into two families, the Argasidae 

 and Ixodidae, which are distinguished from each other by their external 

 structure as well as by their habits 2 . 



General considerations regarding the Biology of the Argasidae 



and Ixodidae. 



The Argasidae are mostly inhabitants of warm climates. When 

 they occur in colder parts of the world they seek hosts whose habitats 

 afford them protection, and insure them possibly a certain degree of 



1 Read before the Cambridge Philosophical Society Meeting, 20 February, 1911. 



2 The main structural differences are described by Nuttall and Warburton (1908) in 

 Ticks, Part I, p. 1. 



