502 Mr. H. A. Baylis on 
is rather small for B. bipunctatus, and the determination is 
somewhat uncertain. 
Abothrium infundibuliforme (Rud.). - 
Host: Salmon. Yukanski, 11. vil. 1917. 
A large number of specimens of this species were found 
hanging out of, and blocking up, the pyloric appendages of 
the intestine of the fish. 
Plerocercoid Larve. 
Hosts: Cottid fishes. Yukanski, 29. vi. 1917 and 
22s Vill OL. 
Larval forms, apparently of two species of Bothrio- 
cephalidee, 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. 
Tetrabothriide. 
Tetrabothrius intrepidus, sp.n. (Figs. 1 & 2.) 
Host: Uria gr#lle (black guillemot). Yukanski, 27. vi. 
£917. 
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, A.) at 
either side of the scolex, between the dorsal and ventral 
suckers. Anteriorly the scolex bears a slight papilla 
(figs LP). 
Segmentation begins close behind the scolex ; the segments 
are much wider than long throughout. The genital pores 
are all situated on theright side. The male and female ducts 
open at the base of a large muscular cloaca (fig. 2, Cl.), 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 
