470 ARACHNIDA ACARINA CHAP. 



of Boophilus are parasitic on cattle the world over, and B. annu- 

 latus is 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. 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 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 . Hyalomma 

 Generally ornate, o without anal plates . . Amblyomma 



4. Generally ornate, $ without anal plates, but with en- 



larged 4th coxae ..... Dermacentor 

 Unicolorous, 3 with anal plates and normal coxae . 5 



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

 Palpi medium, spiracle comma-shaped . . Rhipicephalus 



6. Capitulum short ; 2nd article of palp projecting laterally Haemaphysalis 

 Capitulum long . . . . . .7 



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

 Generally ornate, broad -oval, on reptiles . . Aponomma 



Neumann has recently revised the Ixodoidea in a series of 

 papers published in the Mdmoires de la Societt zoologique de 

 France, 1 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 the Cambridge University Press. 2 



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 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 Mdm. Soc. Zool. ix., 1896, pp. 1-44. 

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



