MITES. 



101 



By this metamorphosis the forms are enabled to withstand desiccation, while a sli<>-ht 

 exposure to dryness kills the normal forms. The species of Typhlodromus usually 

 occur on plants, where they eat the epidermis of the leaves. 



The Ixomrjji, or family of ticks, embraces the largest individuals of the Acarina. 

 The body is enclosed in a leathery skin, the palpi are four-jointed, enclosing the 

 denticulated beak, which is formed of 

 the chelicerae and labrum. Eyes are 

 sometimes lacking, and the legs are 

 slender, terminating with two claws. 

 Ixodes is the typical and largest genus, 

 embracing the forms commonly known 

 as ticks. These live in the woods, and 

 attach themselves to cattle, dogs, and 

 man whenever they have a chance. 

 Here they suck the blood until the body 

 swells up so that it resembles a pea. 

 Several American species have been 

 described, mostly by Dr. Packard, the 

 White-spotted Tick, Ixodes albipictus, 

 being possibly the best known. The 

 European Ixodes ricinus attaches its 

 eggs to its body by a clear fluid which 

 flows from the mouth, and this, to- 

 gether with the position of the open- 

 ing of the oviduct, which is very far 

 forward, gave rise to the idea that the FlG - * -** t 

 female laid its eggs through the mouth. 



oo o 



The genus Argas, which is blind, contains two well-known species, the A., reflexus 

 of Europe, which is parasitic on birds, especially on doves, and A. persicus, of Persia 



and adjacent countries, which 

 lives in houses, and by its 

 punctures produces convul- 

 sions in man, and it is said 

 that even death has resulted 

 from its sting. Another less 

 known form, Arc/as nif/ua, 

 the Pique, produces distress- 

 ing, and sometimes even dan- 

 gerous, sores on men and 

 cattle. 



But little is known of 

 the American species of the 

 next familv, the ORIBATID^E, 



. Upper and under surface of Argas reflexus, dove-tick, enlarged. ' ' 



though the European species 



have been more extensively studied. These forms have the body hard and horny, 

 the ocelli almost obsolete, the mandibles chelate, and the palpi four-jointed and 

 short. The legs are fitted for walking, and terminate in from one to three claws. 

 The sides of the cephalothorax are frequently expanded, and bear on their edges two 



