SYSTEMATIC POSITION AND CLASSIFICATION. 15 
genera and 6 (possibly 7) species, and the Ixodide, represented by 
8 genera, 36 species, and 3 varieties, as follows: 
Argas (2 species in the United States). 
Ornithodoros (4 species in the United States). 
Rhipicephalus (1 species in the United 
States). 
Margaropus(1species in the United States). 
Rhipicephalinz; Hemaphysalis (2 species in the United 
States). 
Dermacentor (8 species and 1 variety in 
the United States). 
Ixodes (16 species and 2 varieties in the 
United States). 
Ceratixodes (2 species in the United 
Teodre:.. a. States). 
Aponomma (1 speciesin the United States). 
Amblyomma (5 species in the United 
States). 
Argasidze | 
Ixodoidea... 
Ixodide .. 
The type locality of 12 of the recognized species occurring in this 
country is outside of the United States. Of these 12 species 2 were 
described by Linneeus (1758), 2 by Fabricius (1794), 1 by Leach (1815), 
3 by Koch (1844), 1 by Guérin (1849), 1 by Cambridge (1876), and 2 
by Dugés (1883). 
Many of the names of supposedly new species have proved to be 
synonyms. Nymphs have occasionally been described as new species. 
The sexual dimorphism and the variation in the amount of blood en- 
gorged at the time the specimens were collected account for many 
of the synonyms. Of the 8 species described by Say in 1821 all 
but 3 are synonyms or remain unrecognized, while of the 5 described 
by Fitch (1872) all are synonyms or remain unrecognized. Of the 
9 described by kerri (1868, 1869, 1872) 5 are recognized as 
distinct species. 
The first work upon iis classification of the ticks of this country 
was that of Dr. Marx (1893), whose studies were soon after ter- 
minated by his death. 
In 1896 Dr. L. G. Neumann published the first part of his revision 
of the Ixodoidea of the world, the last part of which appeared in 
1901, but which has been followed from year to year by a series of 
‘*Notes.”” Unfortunately this valuable work, in its original form, is 
accessible to only a few. However, a concise summary has recently 
been published (1911). 
The first great step in the classification of the ticks of thiscountry 
was taken in 1901, when the important work by Drs. Salmon and 
Stiles, on the cattle ticks of the United States, was published. With 
the appearance, in 1908, of the revision of the Ixodoidea of the United 
