In addition to African genera discussed herein, several others 

 have beeft described from other continents, chiefly by Schulze. 

 Many of these genera, however, meet with little general acceptance 

 among contemporary specialists, A useful summary, including 

 Schulze's and others* genera, may be found in Baker and Wharton 

 (1952). In genersil, however, '"textbook genera"', as used by Neiu 

 mann and by Nuttall and War burton, usually suffice and are of 

 considerable practical and scientific value. They should be 

 little tampered with if at all. Special groups of ticks may be 

 readily categorized at the subgeneric level to provide a usefiiL 

 sounding board for their acceptance by specialists, 



Ixodid ticks occur throughout the world wherever terrestrial 

 vertebrates are fovind. They attack most lajid mammals and some 

 marine forms. Some ixodids parasitize birds and reptiles, some 

 feed on amphibians. Adults of few if any ixodids regard man as 

 a host of predilection but majiy attack him in the absence of other 

 available hosts. Larvae and nymphs are much more common and se- 

 rious pests of man than adults. 



Morphologically, these ticks differ from argasids by the 

 presence in all stages of a dorsal scutum, Ixodid mouthparts 

 are always anterior and visible from above; the body is oval. 

 Larvae have six legs; nymphs have eight legs and a female type 

 scutum but lack both porose areas on the beisis capituli and the 

 genital apertiire of the female. The female scutum covers only 

 the anterior portion of the dorsum, the male scutum extends to 

 the posterior margin of the body. Eyes may be present or ab- 

 sent. Nymphs and adults have a spiracular plate sittiated lateral- 

 ly, posterior of each hind leg. Palpi, clearly segmented and 

 movable in argasids, are limited in ixodids to segments 2 and 

 3 and to a more or less well developed segment 1; segment U is 

 inserted ventrally into a pit of segment 3, 



Biologically, the majority of ixodids display con^jarative 

 ixniformity within rather narrow limits. Exceptions are notorious 

 but few. The number of species is small, somewhere around five 

 hundred, Ixodids are highly adapted to parasitic life but one 

 is prone to wonder how they have succeeded in the battle for 

 survival. Their aimless wajndering habit and dropping from hosts 

 and their indiscriminate oviposition proves fatal to many indi- 



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