502 Mr. H. A. Baylis on 



is rather small for B. bi'punctatus, and the determination is 

 somewliat uncertain. 



Abothrium infundibuliforine (Rud.). 



Host^: Salmon. Yukanski, 11. vii. 1917. 



A large number of specimens of this species were found 

 hano^ing out of, and blocking up, the pyloric appendages oE 

 the intestine of the fisli. 



Plerocercoid Larvce. 



Hosts : Coltid fishes. Yukanski, 29. vi. 1917 and 

 22. vii. 1917. 



Larval forms, apparently of two species of Botlirio- 

 cephalid?e, occurred in two of the fishes examined. One 

 form (A) has a distinct head with pronounced lateral grooves ; 

 two examples of this were found at the surface of the liver. 

 In the other form (B) the head is not distinctly marked off 

 and the suckers are obscure. 



B. Cyclophyllidea. 

 Tetrabothriidae. 



Tetrabothrius intrepidus, sp. n. (Figs. 1 & 2.) 



Host : Uria grylle (black guillemot). Yukanski, 27. vi. 

 1917.^ 



This species is represented only by a single scolex and 

 some fragments. The length of a complete specimen is 

 unknown. The maximum width is 3 mm. The scolex 

 (fig. 1) is 0*6 mm. in width. The suckers are large, depen- 

 dent, and widely open, curling outwards posteriorly, and 

 resembling shallow basins. Auricular appendages are repre- 

 sented only by a slight finger-shaped lobe (fig. 1, 4.) at 

 either side of the scolex, between the dorsal and ventral 

 suckers. Anteriorly the scolex bears a slight ])apilla 

 (fig. 1, P.). 



Segmentation begins close behind the scolex ; t!ie segments 

 are much wider than long throughout. The genital pores 

 are all situated on the right side. The male and female ducts 

 open at the base of a large muscular cloaca (fig. 2, CI.), on a 

 papilla which projects into it. The cirrus-sac (fig. 2, C.S.) 

 is squat, triangular in horizontal section, and has a thick 

 muscular wall. 



The testes number about fifty, extending across the dorsal 



