430 



BUREAU OF ANIMAL INDUSTRY. 



1. 



The chief characters which I have found of use in distinguishing the various 

 species studied are: (1) The furrows of the dorsal shield of the female; (2) the 

 number of rows of teeth to the labium or hypostome; (3) the form of the mandi- 

 bles, particularly the lesser process (the internal apophysis of Neumann); (4) the 

 extent of the dorsal shield of the male; and (5) the presence or absence of a " tail " 

 to the male. 



The following tables indicate the bearing of these features upon the species: 



A. Furrows of the dorsal shield of the female extending to the posterior lateral 

 margins: R. annulatus, caudatus, Evertsi, decoloratus, and australis. 



B. Furrows becoming obsolete in the middle of the shield at about half its 

 length: R. pulchellus. 



(This feature remoYes pulchellus from all others.) 



(A. Labium, or hypostome, with ten rows of teeth: R. caudatus (Neumn.). 

 B. Labium, or hypostome, with eight rows of teeth: jR. annulatus and australis. 

 C. Labium, or hypostome, with six rows of teeth: R. Evertsi and decoloratus. 



(This feature separates caudatus from the four remaining species and helps to 

 separate annulatus and australis from Evertsi and decoloratus.) 



A. Mandibles with lesser process, bicuspid: R. annulatus. 



B. Mandibles with lesser process, tricuspid (Neumn.): R. Evertsi. 



C. Mandibles with lesser process, bicuspid, and presenting a rounded projection 

 as well: R. decoloratus. 



D. Mandibles with the lesser process, tricuspid, and presenting a rounded pro- 

 jection as well: R. australis. 



(This feature differs in each species; there is a slight similarity between annulatus 

 and decoloratus and Evertsi and australis. ) 



A. Male with the shield extending to the posterior margin: R. annulatus, cau- 

 datus, decoloratus, australis. 



B. Male with the shield not extending to the posterior margin (Neumn.) : R. 

 evertsi. 



(This appears to be a ready feature for distinguishing Evertsi from decoloratus.) 



{A. Male with a distinct horny "tail:" R. caudatus, decoloratus, and australis. 

 B. Male with small caudal protuberance: R. Evertsi. 

 C. Male with no indication of a "tail:" R. annulatus. 



(The absence of a tail to the male of annulatus readily separates it from the 

 other species. ) 



From the differences in the various characters, brought out in the above tables, I 

 have felt myself justified in reestablishing Koch's R. decoloratus, and in regarding the 

 Australian tick as a new species. The following brief descriptions will, I think, suf- 

 fice for the recognition of australis and decoloratus: 



Rhi[pi]cephalus decoloratus Koch {" Uebersicht desArachnidensystems," page 134.) 



Eemale. — When replete, 10-12 mm. in length, and 6-8 mm. in breadth. Color uni- 

 form, slate blue. Shield of the same form as that of annulatus and australis, but 

 smaller; furrows at first converging, then diverging to the posterior lateral margins; 

 median region of a light yellow color, laterals red. Eyes not distinct. Labium with 

 six rows of teeth. Mandibles with lesser process bicuspid, and presenting a rounded 

 process as well. Legs generally yellowish, often red. 



Male, adult.— Fale brown, and almost transparent, sometimes dark brown. Length, 

 2-3 mm. Labium with six rows of teeth. Adanal shields four, of the usual form, 

 but more chitinous than those of annulatus, and prolonged into strong conical points. 

 Abdomen ending in a strong chitinous caudal appendage. 



Habitat.— On horses, cattle, etc. ; Cape of Good Hope. 



