474 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
4 . Dibothrium angustatum Rudolplii. Intestine. [PI. xxiv, figs. 269, a, b, c.] 
Thirty-seven young strobiles, August 21, 1899. These agree closely with Diesing’s synopsis of 
this species: “Head elongate, tetragonal, slender, with oblong lateral bothria; neck very short. First 
segments elongated, very narrow; succeeding segments shorter, subquadrate.” 
The outline of the head varies with the state of contraction, but the prevailing form is linear- 
oblong or somewhat clavate. Segments slender, almost cylindrical, slightly eirlarged at their posterior 
ends. Dimensions of an alcoholic specimen in millimeters: Length of head, 1.16; breadth, anterior 
0. 33. greatest breadth 0.33, posterior 0.19. Another: Length of head, 1.21; breadth, anterior 0.22, 
greatest breadth 0.26, posterior 0.17. Longest head measured 1.92 mm. in length to the first distinct 
segment. The strobiles are linear or nearly so and measured about 25 mm. in length. 
5. Phyllobolhrium sp. Immature. Intestine. [PI. xx, figs. 231, 232.] 
Three specimens collected July 11, 1900, bear some resemblance to larvae which ar e not infrequent 
in the common squid. ( 4 , p. 792, pi. lxii, figs. 1-9.) Llead white, with four bothria, which have 
crumpled borders and an auxiliary acetabulum on anterior border of each. There is also a muscular 
sucker (myzorhynchus) on anterior part of head between the bothria. Neck linear, ligulate, 
translucent, the vessels of water vascular system showing plainly as sinuous lateral lines, in preserved 
specimens, filiform. Body fusiform, appressed, opaque, pinkish. The largest specimen measured in 
life 44 mm. in length. Length of head, 3 mm.; of head and neck, 26 mm.; of body, 18 mm. 
6. Rhynchobothrium sp. Encysted on viscera, especially on pyloric caeca. 7, p. 282. Found also in 
1899 and 1900. 
Immense numbers of small pyriform cysts, 2 to 5 mm. long, were found on pyloric caeca of a silver 
hake, July 11, 1900. Dimensions of one of these larvae in millimeters: Length, 3; length of head, 0.87; 
of contractile bulbs, 1.02; of proboscides, estimated, 1.74; diameter of proboscis, moulding hooks, 0.15; 
length of longer hooks, 0.07; diameter of contractile bulbs, 0.12. The hooks differ from any I have 
yet seen, bearing some resemblance to those of Tetrarhynchus erinaceus. [PI. xxn, figs. 251-254.] 
7. Larval cestodes (Scolex polymorphus Dujardin). Free in intestine. 7, p. 282. See 4 , p. 789, etc. 
Found also in 1899 and 1900. 
TREMATODES. 
8. Distomum ocreaturn Molin. Intestine. See 4 , p. 514, etc. 7 , pp. 282, 288, pi. xxxv, figs. 16-24. 
Found also Aug. 21, 1899; 10. 
9. Distomum vitellosum Linton. Intestine. 7 , pp. 282, 290. Found Aug. 21, 1899; 18. [PI. xxx, 
fig. 335.] 
Pollachius virens, Pollock. 
NEMATODES. 
1. Ascaris clavata Rudolphi. Stomach. 7 , pp. 283, 302, pi. xliii, figs. 105-108. 
In the U. S. National Museum collection there are three specimens from the pollock which 
evidently belong to this species. While they, together with those from the cod, present many 
variations, they agree in having the posterior end truncated and the upper lip oblong with a somewhat 
cylindrical pulp. The side membranes were not easily seen in all. The adults of both sexes are more 
attenuate anteriorly than posteriorly, while the males are shorter and relatively stouter than the 
females. See under Gadus callarias , No. 2. 
la. Immature nematodes. 
Six lots in LL S. National Museum collection from body cavity. Specimens inclosed in embryonic 
cuticle. Length about 24 mm., head truncate, tail with mucronate tip. Collected in October and 
November, 1886. 
CESTODES. 
2. Rhynchobothrium. Larvae encysted on mesentery. 7 , p. 283. 
TREMATODES. 
3. Dactylocotyle denticidatum Olsson. [ Octobothrium denticulatmn Olsson.] Gills. 7 , pp. 283, 286, pi. 
xxxin, figs. 6-10. 
