4/0 ARACHNIDA ACARINA CHAP. 



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

 /itf.ns is the transmitter of Texas fever. Rhipicephalus and 

 AmUyomma 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 Ehipicentor, 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 011 the lateral borders of the scutum . . 2 

 No eyes . . . . . . . .6 



2. Cfipitulum long, much longer than broad . 3 

 Capitulum short . . . . . .4 



3. Unicolorous, <J 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 . . . Boopliilus 

 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 . Txodes 

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



Neumann has recently revised the Ixodoidea in a series of 

 papers published in the Mfanoires de la Societe zoologique cle 

 France, 1 but the work is not obtainable as a whole. A mono- 

 graph, by Nuttall, Warburton, Cooper, and Eobinsou, 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. 



' The first paper appeared in M't'ni. Soc. Zool. ix., 1896, pp. 1-44. 

 2 "Ticks, a .Mcmognipli of the Ixodoidea." Part I. Argasidac, 1908. 



