Acarina 271 



pp. Hind part of the male abdomen without 

 lobes. Live in ears of dogs and cats 



Otodectes Canestr. 



0. cynotis Hering (fig. 150 e) has been 



taken in the United States. 



2. Palpi usually of four or five segments, free; rarely with ventral 



suckers near genital or anal openings; eyes often present; tarsi 



never end in suckers; body usually divided into cephalothorax 



and abdomen; rod-like epimera rarely visible; adults rarely 



parasitic. 



f. Last segment of the palpi never forms a thumb to the preceding 



segment; palpi simple, or rarely formed to hold prey; body 



with but few hairs EUPODOIDEA. 



g. Palpi often geniculate, or else fitted for grasping prey; mandi- 

 bles large and snout -like; cephalothorax with four long 

 bristles above, two in front, two behind; last segment of leg I 



longer than the preceding segment, often twice as long 



Bdellid^. 



gg. Palpi never geniculate (fig. 158a), nor fitted for grasping prey: 

 beak small; cephalothorax with bristles in different arrange- 

 ment; last segment of leg I shorter or but little longer than 

 the preceding joint; eyes when present near posterior 



border EUPODID.ffi; 



Moniez has described a species from Belgium (Tydeus 

 molestus) which attacks man. It is rose colored; eye- 

 less; its legs are scarcely as long as its body, the hind 

 femur is not thickened; the mandibles are small and the 

 anal opening is on the venter. The female attains a 

 length of about 0.3 mm. 

 ff. Last segment of the palpus forms a thumb to the preceding, which 

 ends in a claw (with few exceptions) ; body often with many 



hairs (fig. 158 k) TROMBIDOIDEA. 



g. Legs I and II with processes bearing spines; skin with several 



shields; coxae contiguous Cmcvlitim. 



gg. Legs I and II without such processes; few if any shields. 



h. Palpi much thickened on the base, moving laterally, last 



joint often with two pectinate bristles; no eyes; legs I 



ending in several long hairs; adult sometimes parasitic 



CHEYLETID.ffi; 



Cheyletus eruditus, which frequents old books, has once 

 been found in pus discharged from the ear of man. 

 hh. Palpiless thickened, moving vertically; eyes usually present; 

 leg I not ending in long hairs, 

 i. Coxae contiguous, radiate; legs slender, bristly; body with 



few hairs; no dorsal groove; tarsi not swollen 



Erythr^id^. 



ii. Coxae more or less in two groups; legs less bristly. 



