426 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol.2 



Ceratixodes {putus and signatus) apparently occur in the Boreal Zone 

 only. Many of the species which occur in this country appear to be 

 limited to the Transitional and Austral Zones, but a more extensive 

 ' collection is necessary to determine their exact distribution. 



The host relations of ticks are an important factor to be considered 

 in the study of their geographical distribution. Some species remain 

 attached for long i^eriods and can be carried great distances. The 

 males in many species remain upon the host long after the females, 

 which attached at the same time, have dropped. Many records have 

 been based upon such accidental introduction of the species with the 

 host and should not be considered in determining the normal distri- 

 bution of the species. Unless the species can reproduce itself and 

 continue reproduction from year to year it should be looked upon 

 as an accidental introduction and temporary resident. In such in- 

 stances man is usually responsible for the introduction, which is 

 largely upon domestic animals. Thus Margaropios annulatus has 

 frequently been introduced into the northern states, where it can 

 reproduce during the summer, but is killed by the cold of winter. 

 It was found by Banks in a collection from Michigan, where it had 

 been taken from ponies. AniMyomnia dissimile, which was intro- 

 duced into Brownsville, Texas, from the Isthmus of Tehuantepec, on 

 iguanas, is another instance of an accidental introduction which will 

 probably fail to become established. 



A more extensive collection will undoubtedly show a much wider 

 distribution and common occurrence of many of the species here 

 recorded. For the present the determination of their normal dis- 

 tribution must be based upon the frequence of their occurrence, par- 

 ticularly that of females. 



Explanation of Abbreviations 



Aragao 1908.=Included in a list of Brazilian ticks furnished the 

 writer by Dr. Henrique B. Aragao. 



B. A. I. Coll.=In the collection of the Bureau of the Animal Industry, 

 U. S. D. A. 



B. A. I. Quar. Area=Included in the area quarantined by the Bureau 

 of Animal Industry, U. S. D. A. 



B. E. Coll.=In the collection of the Bureau of Entomology, U. S. 

 D. A. 



Bks. Coll.=In the private collection of Llr. Nathan Banks. 



Bks. Rev.=Recorded in Banks' Revision of the Ixodoidea. 



Bks. 1902=Banks' account in Papers from the Hopkins Stanford Gal- 

 apagos Expediton, 1898-1899, Proc. Wash. Acad. Sci. IV. 



