470 ARACHNIDA ACARINA chap. 



of BoopMlus are parasitic on cattle the world over, and B. anmi- 

 latus is the transmitter of Texa^s fever. Wiijncephalus and 

 AmUyomma are large genera which include several species 

 of economic importance. For example, B. sanguineus conveys 

 canine piroplasmosis, and A. hebraeum 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 Bhipicentor, 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, S with chitinous plates near anus . Hyalomma 

 Generally ornate, o without anal plates . . Amhlyomma 



4. Generally ornate, $ without anal j^lates, but with en- 



larged 4th coxae ..... Dermacentor 

 Unicolorous, ^ with anal plates and normal coxae . 5 



5. Palpi very short, spiracle circular . . . Boophilua 

 Palpi medium, spiracle comma-shaped . . Rhipicephalus 



6. Capitulum short; 2nd article of palp jirojecting laterally Haemaphy salts 

 Cai^itulum long . . . ... 7 



7. Unicolorous, elongate, on birds or mammals . Ixodes 

 Generally ornate, broad-oval, on reptiles . . A'ponomm.n 



Neumann has recently revised the Ixodoidea in a series of 

 papers published in the M&moires de la Society zoologique de 

 France} but the work is not obtainable as a whole. A mono- 

 graph, by Nuttall, Warburton, Cooper, and Eobinson, is now in 

 course of publication at tlie Cambridge University Press." 



Fam. 4. Gamasidae. — The Gamasidae are carnivorous Mites, 

 either free-living 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-families are Gamasinae, Uropodinae, and 

 Dermanyssinae. 



Of the Gamasinae, Gamasus coleoptixitorum is the well-known 

 Beetle-parasite so frequently seen on Geotrupes. It is often con- 

 founded with another species of similar habits, G. crassipes. 



^ The first paper appeared in Man. Soc. Zool. i.\., 1896, i)p. 1-44. 

 * "Ticks, a Monograph of the Ixodoidea." Part I. Argasidae, 1908. 



