ACARINA. 



843 



basal segments of the pedipalps are united behind the mouth, but 

 those of the following segments are widely separated and have no- 

 gnathobases. Respiratory stigmata, when present, are usually 

 cephalothoracic. 



The mites are divided up in a very large number of species r 

 not perhaps so many as are the spiders, but into far more than 

 any other Arachnid group. They also at times show a most 



FIG. 554. Ripe male of Atax Bonzi, seen from the dorsal surface (after E. Claparede). Kt 

 Pedipalpus ; G brain ; Oc eyes ; T testis ; N Y-shaped gland ; D intestine ; A anus ; 

 Hd cutaneous glands. 



rapid rate of reproduction and hence if conditions are favourable 

 very large numbers of individuals are met with. 



They are for the most part minute, except the ticks, which 

 swell visibly after a meal of blood. Mites seldom surpass a 

 millimetre in length, whilst many are microscopic. 



clmes en part," Ann. des Sc. Nat., ii. Ser., Tom. i. and ii. H. Nicolet, 

 " Histoire naturelle des Acariens, etc. Oribatides." Archives du Musee 

 d'hist, Nat., Tom. vii. O. Fiirstenberg, " Die Kratzmilben des Menschen 

 und der Thiere," Leipzig, 1861. Al. Pagenstecher, " Beitrage zur Anatomie 

 der Milben," i. and ii., Leipzig, 1860-1861. E. Claparede, " Studien an 

 Acariden," Zeitschr. fur wiss. ZooL, Tom. xviii., 1868. P. Megnin, " Les 

 parasiteset les maladies parasitaires," 1880. A. D. Michael, " Oribatidae " 

 Das Tierreich Lief. iii. A. Nalepa, " Eriophyidae (Phytoptidae)," op. 

 cit. Lief. iv. G. Canestrini, nnd P. Kramer, "Demodicidae und Sarcop- 

 tidae," op. cit. Lief. vii. R. Piersig, nnd H. Lohmann. " Hvdraehnidae 

 und Halacaridae," op. cit. Lief. xiii. 



