SEVENTEENTH ANNUAL REPOET. 



461 



Several species occur in America, and two of them, Ixodes ricinus and 

 / hexago7ms. occur on American cattle. Neumann gives the following- 

 key to the species known to him: 



Key to the Species of the Genus Ixodes. 



[For North American forms, follow Roman type.] 



Males - 1 



Females - 9 



Nymphs 35 



A. — Male. 



1. Anal shield with divergent or parallel sides 2 



Anal shield with convergent sides 7 



2. Scutum covering the greater part of the back 3 



Scutum scarcely covering half of the width of the back (South America) . I. loricatus. 



3. Posterior margin of scutum not fimbriate 4 



Posterior mf.rgin.of the scutum divided into 5 short broad segments provided 



with long hairs (Bering Island) /. fimbriatus. 



4. Coxse I with strong median spine 5 



Coxx I: Median and lateral spines short and equal (Egypt) I. coxxfurcaius. 



5. Tarsi without dorsal protuberance 6 



Tarsi with dorsal protuberance near the tip /. hexagonus, p. 467 



6. Scutum pubescent /. ricinus, p. 462 



Scutum glabrous (Japan, Amoor) J. ovatus. 



7. Anal shield open caudad 8 



Anal shield closed caudad (Congo) 1. rasus. 



8. Anal shield horseshoe-shaped (Africa) /. pilosus. 



Anal shield nearly closed caudad (Australia, India) 1. holocyclus. 



B. — Female 



9. Anal grooves divergent or parallel 10 



Anal grooves convergent 34 



10. First palpal article short, not forming an anteriorly directed horn 11 



First palpal article forming a strong anteriorly directed horn (South America) 



/. thoracicus. 



11. Scutum longer than broad 12 



Scutum as broad as long, or broader than long 30 



12. Sides of scutum rounded 13 



Sides of scutum straight, angular, or sinuous 25 



13. Lateral grooves of scutum more or less apparent 14 



Lateral grooves of scutum absent 21 



14. Coxae I with one spine or with two unequal spines 15 



Coxse I with two equal spines (South America) /. loricatus. 



15. Coxae I with strong median spine 16 



Coxse I not prolonged in a strong median spine 17 



16. Punctations of scutum equal 18 



Punctations of scutum unequal, the larger near the margin /. diversifossus. 



17. Coxx I with small spine at postero-lateral angle (South America) . . . /. frontalis var. 

 Coxse I without spine at postero-lateral angle (Congo) /. rasus. 



18. Porose areas broader than long and close together /. ricinus, p. 462 



Porose areas as long as broad, or longer, distant 19 



19. Lateral grooves of scutum slightly apparent; purwtafiovs fine {J £i\)an, Amoor) , /. oraivs. 

 Lateral grooves well marked 20 



11359—01 30 



