frequently foiind on other animals. Reasons for these differences 

 are beyond our present ability to explain. 



Immature stages of many rhipicephalid species remain vox. 

 described and distintjuishing criteria for a nvimber of those that 

 are known are insufficient for identification of field collected 

 material. 



Ecological stratification is quite restricted, various spe- 

 cies being confined to forests, highlands, semidesert areas, or 

 certain rainfall conditions. The degree and distribution of 

 relative humidity appear to be the most critical of limiting 

 factors. Vegetation types associated with this factor and in- 

 fluenced by the length of the rainy season or proximity to 

 moisture laden air beside the seas can often be associated with 

 rhipicephalid distribution. 



Economically, many species are of considerable importance as 

 reservoirs and vectors of a variety of animal and some human 

 pathogens. The kennel tick, R. s. sanguineus , has been shown to 

 have a particvilarly wide specTnim of actual or potential relation- 

 ships as a vector of diseases. 



- 585 - 



