I NATHAN BANKS. 



tip and divided into sj)ine.s more often it is wholly united to the 

 ceplialothorax and only lateral lines or ridges mark its position ; at 

 its tip there is nearly always a pair of bristles, the anterior bristles ; 

 and above near base another 2)air is often ])resent, the sui)erior bris- 

 tles. Near each })osterior angle or corner of the cephalothorax is a 

 roiuid spot or pore ; from it arises a seta, often clavate ; these pores 

 are supposed to be the breathing stigmata. The legs arise from the 

 underside of the cephalothorax, the posterior pairs apparently coming 

 from the abdomen ; the coxse are often more or less united into a 

 plate, the coxal plate ; but there is no real sternum. The legs con- 

 sist of a coxa, a trochanter, longer femur, a short patella, a long 

 tibia, and a metatarsus and tarsus ; the latter two are often more or 

 less united. The claws yary from one to three in numbei*. The ab- 

 domen is of various shapes, often quite globose ; the dorsum is sepa- 

 rated from the venter by a lateral line which is really double. In 

 some forms the base of the abdomen bears lateral expansions of the 

 tegument, these are called wings. On the venter are two apertures, 

 the basal one is the genital opening ; the apical one, the anal open- 

 ing ; they are closed by two laterally hinged plates meeting on the 

 median line. 



The young are soft-bodied mites, often obovate in form, and some- 

 times with curious markings. In those species which have three 

 tarsal claws the young usually have but one claw. The young have 

 frequently been mistaken for adults and described under various 

 genera, as 3fureia, HypocMhoniu^, Claviceps, Alichcelia, etc. The 

 mite upon attaining the adult structure is not necessarily adult ; at 

 least they moult several times afterward. These young, but not 

 larval forms are usually paler than the adult, but otherwise do not 

 differ, except in size. According to Michael, who has studied the 

 British species of this family very carefully, the young may be born 

 in four ways : I, as in the insects, the eggs laid and after a time 

 hatching ; II, the eggs hatching as soon as laid ; III, the eggs 

 hatching just before extrusion, ovo-vivi parous ; IV, the eggs never 

 being laid, but hatching within the parent some time after the latter's 

 death. 



The species are all small, rarely one millimetre long. They occur 

 in many situations, but none, so far as I know, regularly inhabit 

 houses or other buildnigs. Some occur under the loose bark of dead 

 trees, others on the bark ; some on plants, as grass and weeds in 

 meadows ; sometimes even in flowers. Some occur in decaying 



