470 ARACHNIDA—ACARINA CHAP. 
of Boophilus are parasitic on cattle the world over, and B. annu- 
latus 1s the transmitter of Texas fever. Rhipicephalus and 
Amblyomma are large genera which include several species 
of economic importance. For example, R. sanguineus conveys 
canine piroplasmosis, and A. hebraewm causes “heart-water” in 
South African cattle. The genus Aponomma confines its atten- 
tion to reptiles, and some of its species are exceedingly ornate. 
Neglecting Margaropus and Rhipicentor, which include only 
a very few aberrant forms, the following entirely artificial key 
will serve to differentiate the genera of the Ixodidae :— 
1. A pair of eyes on the lateral borders of the scutum 2 
No eyes 6 
2. Capitulum long, much longer than broad 3 
Capitulum short : ‘ 4 
3. Unicolorous, ¢ with chitinous plates near anus 2 Fees 
Generally ornate, ¢ without anal plates : . Amblyomma 
4, Generally ornate, ¢ without anal plates, but with en- 
larged 4th coxae. : . Dermacentor 
ereolancns 6 with anal plates and onal coxae pe 
5. Palpi very short, spiracle circular : : .  Boophilus 
Palpi medium, spiracle comma-shaped_ . 3 Rhipicephalus 
6. Capitulum short; 2nd article of alp projecting laterally Huemaphysalis 
Capitulum long : : : ee 
7. Unicolorous, Blonpate, on birds or mammals : Ixodes 
Generally ornate, “cecil -oval, on reptiles ‘ . Aponomma 
Neumann has recently revised the Ixodoidea in a series of 
papers published in the JMlémoires de la Société zoologique de 
France,’ but the work is not obtainable as a whole. A mono- 
graph, by Nuttall, Warburton, Cooper, and Robinson, is now in 
course of publication at the Cambridge University Press.” 
Fam. 4. Gamasidae.—The Gamasidae are carnivorous Mites, 
either free-lving or parasitic on animals. The chelicerae are 
chelate, and the palps are free. The tarsi have two claws, 
accompanied by a “caruncle” or sucking disc. They are mostly 
pale-coloured Mites, with a smooth, more or less scutate covering. 
The three principal sub-familhes are Gamasinae, Uropodinae, and 
Dermanyssinae. 
Of the GAMASINAE, Gamasus coleoptratorum is the well-known 
Beetle-parasite so frequently seen on Geotrupes. It is often con- 
founded with another species of similar habits, G. crassipes. 
1 The first paper appeared in M/ém. Soe. Zool. ix., 1896, pp. 1-44. 
” Part I. Argasidae, 1908. 
9 
* “Ticks, a Monograph of the Ixodoidea. 
