506 Mr. H. A. Baylis on 



for diagnosis, are unknown. The species differs from C/i. 

 horealls (v. Linst.) in having; forty-five to forty-eight testes, 

 instead of t\Yenty-five, in eacli segment, and also in liaving 

 a smaller scolex (0'-i3 mm. across at the suckers, instead of 

 0-67 mm.). 



Anomotcenia campyTacantha (Krabbe), Zschokke, 1903. 



Host: Uria gryJle. Yukanski, June and July 1917. 



Numerous examples of a worm which may be referred to 

 this species occurred in several black guillemots, associated 

 in one case with Tetrahothrius intrepidus. They usually 

 occupied the upper part of the intestine, just below the 

 gizzard. 



Anomotcenia micracantha (Krabbe), Zschokke, 1903. 



Host: Uria civylle, Yukanski, 22. x. 1917. 



A second and rather larger species, which I refer to 

 A. luicracanth.a, occurred in considerable numbers in one of 

 the same birds in a similar position to the preceding form. 



MonopyUdium arcticinn, sp. n. (Figs. 3 & 4.) 



Host: Tr'inqa markima (purple sandpiper). Yukanski, 

 7. viii. 1917. 



This is a slender little worm^ about 35 cm. long when 

 fairly extended. The maximum width (at the posterior end 

 of the strobila) is about 0'5 mm. A peculiar feature is the 

 tendency of the neck to be very much conti acted in the 

 longitudinal direction (fig. 3, B) and very wide just behind 

 the scolex. Nearly all tiie specimens show this contraction, 

 which gives them, to the naked eye, the appearance of having 

 a very large, flattened f-colex. 



Tlie scolex (fig. 3, A) measures about 0*24 mm. across the 

 suckers, the diameter of the latter being 0T2 mm. The 

 rostellum has a mu.-shroom-siiaped end and a fleshy and 

 muscular stalk. There is a single row of about thirty (?) 

 hook.*, measuring about 15 p, in length. There is a pair of 

 glandular (?) structures (fig. 3, A, G.) at the base of the 

 rostelkim, in the sid^stance of tlie scolex. 



The strobila contains some eighty segments, which are 

 considerably longer tiian broad, except those near the anterior 

 end. They gradually increase in length towaids the posterior 

 end, some of the gravid segments being fully three times as 

 long as broad. The longitudinal musculature is very well 

 developed. Mature segments (fig. 4) begin to appear at 



