( l(i7 ) 



top, the rounded npper margin being shorter.* The proximal lobe of the ninth 

 sternite is anteriorly rounded in wickhdud (PI. VI. fig. 8), while it is sharply 

 angnlate in aeqer (PI. VI. fig. 7). The spine situated on this lobe is thinner in the 

 new species, and the large apical portion of the ninth sternite is shorter and 

 broader in irirkliand than in ae(/er, while the manubrium of the clasper is broader 

 in the new species than in wiclthami. 



In the female the longest apical liristle on the posterior side of the first 

 hindtarsal segment reaches beyond the insertion of the subapical pair of the second 

 segment. The corresponding bristle of this latter segment extends almost to the 

 liase of the apical bristles of the third, while these bristles are shorter in icickhami. 

 The sinus of the seventh sternite (PI. VI. fig. 9) is rather wider, and the spine-like 

 bristles at the lower edge of the eighth tergite thinner, than in unckhami. 

 We have four examples of this insect, collected by Mr. G. F. Dippie ;— 

 2 S 6, Red Deer, Alberta, May 22nd, 1901. Peromyscus arcdcus. 



1 + > )) )> )I >> I> !> )I I) 



1 ? , ,, „ „ April 28th, „ Evotomi/s saturatiis. 



11. Ceratophyllus agilis spec. nov. (PI. VII. figs. 10, 17, 18). 



This species is closely allied to C. sexdentatus Baker, of which we have one 

 pair kindly given us by the author. The differences between the two insects are 

 slight, but quite constant iu our series of Ceratophijllus agilis. It is probable that 

 intermediate specimens will be found in other localities confirming our supposition 

 that we have here to do with varieties rather than with distinct species. 



Both sexes differ from sexJeittatas in the longest apical bristle on the hinder 

 side of the first hindtarsal segment reaching nearly to the apex of the second 

 segment. This bristle extends iu sexdentatus hardly beyond the subapical pair of 

 l)ristles. A further difference is that the hindtibia bears five or six hairs on the 

 inner surface instead of three. The male, moreover, can be distinguished by the 

 following characters. In Cenitophyllus agilis the eighth tergite bears behind and 

 below the stigma about fifteen bristles (PI. VII. fig. 17, viii. t.), while in sexdentatus 

 there are only eight or nine, inclusive of some very small ones (PI. VII. fig. 15, viii. t.). 

 The finger (PI. VII. fig. 16) bears in Ceratophi/llus agilis only five spines instead of 

 six. The proximal lobe of the ninth sternite is rectangular proximally. 



Apart from the longer apical bristle of the first hindtarsal segment and the 

 larger number of bristles on the innerside of the hindtibia, there is apparently 

 nothing by which to distinguish the female of agilis from that of sexdentatus. 

 The seveuth.sternite (PL VII. fig. 18, vii. st.) is very deeply sinuate, being produced 

 above the sinus into a long finger-like lobe, which varies somewhat in outline. The 

 position of the bristles on the eighth tergite is shown in the figure referred to. 



Length : S, 2-5 mm. ; ? , .3 to 3-4 mm. 



We have a very large series of this sjiecies, as follows : — 



2 c?c?, Banff, Alberta, August 8th, 1899. ]S!eotom,a cinerea. (G. F. Dippie.) 

 4 2 9 



10 cJ(J, „ „ „ 9th, „ Bushy-tailed AVood-rat. „ 



11) + + , ,, ,, ,, ,, ,, ,, ,, )> 



* In Baker's fiftme the finger is drawn narrow at tlic tnp and sbarply truncate. In a male received 

 from Mr. IJakcr, and in our otticr two innlrs of n-ir/i/uiiii!, the finger is much broader and mnch more 

 rounded at the top tliau iu Bak figure. 



