626 MEDICAL ENTOMOLOGY 



spurs, the external conical ; coxae II and III with two short spurs ; coxa 

 IV much longer than broad, with the spur at the antero-external angle, 

 and one external spur. Spiracle with the postero-external extension well 

 developed. Length 5 mm. ; width 3 mm. (Neumann) 



Female- (Plate LXXX, fig. 4) Scutum a little longer than broad ; 

 posterior border sinuous ; eyes towards the middle of its length. Cervi- 

 cal grooves long and .deep ; lateral grooves wanting. Porose areas deep, 

 diverging anteriorly and converging posteriorly. Length 5 to 12 mm. ; 

 width 3 to 8 mm. (Neumann) 



This species is found in the United States, particularly in Montana ; 

 it is -parasitic on horses and cattle, and often attacks man. It is the 

 invertebrate host of the parasite (?) of Rocky Mountain Spotted Fever. 

 According to Stiles it has been previously described under the name 

 Dermacentor occidentoHs, Marx ; it is also spoken of as Dennacentor 

 ven nst us, Marx. 



Dermacentor varidbills, Say. Male. Scutum chestnut brown with 

 white spots and deep subrequal scattered punctations. Hypostome with 

 six rows of teeth. Palpi longer than broad without dorsal retrograde 

 spines. Coxa I has two well-developed contiguous spurs, the external 

 conical; coxae II and III each have two short spurs. Coxa IV is a little 

 longer than broad, and the spur is situated towards the posterior third. 

 Length 5 mm. ; width 2*5 mm. (Neumann) 



Female. Scutum a little longer than broad with a concave border 

 posterior to the eyes, which are situated about the middle of its length. 

 Cervical grooves deep, united anteriorly with the lateral grooves, 

 which are also deep. Porose areas deep and converging posteriorly. 

 Length 5 to 14 mm. ; width 2'5 to 9 mm. (Neumann) 



This species is found in Mexico and the United States ; it is parasitic 

 on the cattle, the horse, hare, dog and lynx. Neumann recognizes one 

 variety, panimapertns. 



As already pointed out, Dennacentor reticulatus is believed to be the 



invertebrate host of Piroplasma canis in Europe, and it is also said to 



Relation to Disea transmit P. equi in Russia. Dennacentor andersoni, 



Stiles, transmits the infective agent of Rocky Mountain 



Spotted Fever, a disease which affects man in the Bitter Root Valley 



in Montana, United States. The disease is not localized to Montana, 



but also occurs in Washington, Oregon, Idaho, California, Alaska, 



Nevada, Utah, Colorado and Wyoming. 



Bishop and King, in a recent paper, give some data regarding the life 

 processes of Dermacentor andersoni. The adult ticks, though present 



