GENUS IXODES LATREILLE. 23 



3. Shield about one and one-lialf times longer than broad: all coxa with 



spines; second joint of palpus about four times as long as broad; 

 porose areas occupying greater part of capitulum ; a small tooth at 



base of each palpus hrunneus. 



Shield but little longer than broad; only coxa I spinetl (in female); 

 second joint of i)alpus scarcely three times as long as broad; porose 

 areas smaller '^ 



4. Shield not angalate on sides, no lateral cariujTe; porose areas separated 



by fully their length; tarsus I rather shorter scfipuhins. 



Shield slightly angulate on sides, with traces of lateral carina 



5. Porose areas large, separated by less than their length ; coxa I with 



very long spine ricinus. 



Porose areas smaller, more widely separate; coxa I with shorter spine; 

 shield more rhomboidal calif ornicus. 



6. Shield with definite lateral carinee T 



Shield without definite lateral carlnte; coxa I with a short spine 11 



7. A large tooth each side under rostrum ; coxa I with one long spine 10 



No such teeth under rostrum S 



8. Shield fully one and one-half times as long as broad ; coxa I with rather 



short spine; porose areas triangular angustiis. 



Shield not one and one-half times as long as broad; coxa I with long 

 spine; porose areas not triangular 9 



9. Porose areas as long as broad, the area separating them with a 



scar sculpt us. 



Porose areas broader than long, no scar between them cookei. 



10. Shield mirrowed behind; hind angles of capitulum very prominent; 



porose areas broader than long, very small pratti. 



Shield very broad behind; hind angles of the capitulum barely distinct; 

 porose areas nearly as long as broad dcntatus. 



11. Shield finely punctate, about one and one-half times as long as broad; 



third joint of palpus longer than broad; porose areas small, sep- 

 arated by their width marxi. 



Shield coarsely punctate, barely longer than broad ; last joint of palpus 

 about as broad as long; porose areas larger, not seiiarated by 

 width hexngnnus. 



Ixodes arcticus Osborn. 



This was described from one specimen taken from a seal from the 

 Pribilof IsLands. It is recorded (No. 3500) in the type catalogue of 

 the Division of Insects, U. S. National Museum, but diligent search 

 on several occasions has failed to discover the specimen, therefore 

 I am compelled to copy the description of Professor Osboni, which 

 is not as specific as I could wish, yet indicates that the species is a 

 good one: 



" Elongate oboval, slightly contracted behind the middle, finely 

 transversely striated ; dorsal shield deep chestnut brown, oval except 

 where truncated to join head; two divergent impressed lines or fur- 

 rows from near the anterior margin to behind the middle, where they 

 terminate abruptly, and external to which, near their ends, are short, 

 impressed lighter marks, one on either side. Palpi rather short, 

 blunt, truncate at apex, sharp edged, flat, and somewhat impressed 



