GENUS ORNITHODOROS KOCH. 17 



2. Two pairs of eyes preseut ; tarsi IV with a prominent subterminal spur 



above; front of body conical in the middle; leg I strongly rough- 

 ened coriaceus. 



No eyes; no such spur on hind tarsi 3 



3. Front of body conical in middle; tarsi I without humi)s above talnjc. 



Body rounded in front ; tarsi and metatarsi each with three humps_<Mrtca(a. 



Ornithodoros megnini Diiges. 



Color red-brown to black, legs paler. Body broadly rounded in 

 front and behind, a constriction much behind the middle. Body 

 covered with many short, stiff, spine-like bristles (PI. I, fig. 12), 

 stouter in front than behind, and on venter mostly hair-like, skin 

 only minutely roughened. Several broad depressions above, and on 

 venter three elongate grooves behind and two in front. Rostriun 

 and palpi (PI. I, fig. 0) short. Legs (PI. I, figs. 10, 11) short and 

 stout; tibia and metatarsus of leg I not twice as long as broad, all 

 tarsi wath a subterminal hump, no other tubercles, hind tarsi not 

 three times as long as broad at base, all legs with a few scattered 

 hairs. No eyes. 



Length of swollen female, T to 8 nun. 



Male similar, but rather smaller and more slender. The nymphal 

 stage (which is frequently observed) has a body about one and a half 

 times as long as broad, broadest in front of leg III, nnich narrowed 

 behind, broadly rounded in front and behind, the body covered with 

 spine-like bristles, larger than on the adult, tlie legs more slender and 

 more hairy. This nymph was first described and figured by Megnin. 

 jNIarx proposed for it the name RhifiKhoprion ^p'nio.smn. 



This species is easily known from all other species of Or)iithodoros 

 by its bristly body, as well as by shape of tarsi. These, with the 

 greater difl'erence between the adult and nymphal instars, indicate 

 that this species might well be the type of a subgenus. First found 

 by Duges in the ears of Mexican horses, it has been taken abundantly 

 in the southwestern part of the United kStates, usually from the ears 

 of cattle, but sometimes from other anintals, including man. 



Specimens have been examined from the following localities: 

 Aycock, La.; Georgetown, San Antonio, and Victoria, Tex.; Albert, 

 Santa Fe, and Mineral Hill, N. Mex. ; Yuma, Ariz. ; Los Angeles, 

 Santa Rosa, Santa Clara County, and Humboldt County, Cal. ; Ash 

 MeadoW', Nev. ; Fremont County, Idaho; Davenport and Ames, 

 Iowa, and Lexington, Ky. 



Its frequent occurrence in ears has won it the connnon name of 

 " ear tick " or " spinose ear-tick." 



