458 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
NEMATODES. 
3. Ascaris sp. [PI. vm, figs. 65-69.] 
A small lot of ascarids in the IT. S. National Museum collection from a scup. which had been taken 
from the stomach of a cero ( Scomber omorus regalis). These are thickest about the middle, rather more 
slender anteriorly than posteriorly; lateral alse for about 1 mm. back of head; tail somewhat slender 
and prolonged beyond the anal aperture, decidedly suppressed; body crossed by fine transverse lines, 
best seen toward posterior end. Dimensions in millimeters: Length, 45; diameter of head, 0.23, 4 mm. 
back of head 0.48, 10 mm. back of head 0.68; median, 1.28, 1 mm. from posterior end 0.45, at anal 
aperture (ventral view) 0.28; distance of anal aperture from posterior end, 0.85. 
4. Immature nematodes {Ascaris). [PI. x, figs. 110-116; pi. xi, figs. 117-120.] 
Very common in body cavity on viscera. Found in at least 75 per cent of the scup examined in 
the past two summers; also noted repeatedly in previous years. A careful study of these forms is 
needed in order to fix their position. Some of them with the characteristic head of Agamonema, after 
the removal of the cuticle, revealed the unmistakable jaws of Ascaris. Measurements of one are given 
'in 7 , p. 280. I add, for the purpose of comparison, measurements in millimeters, of a specimen from 
the viscera of a scup collected July 24, 1899: Length, 20; diameter, anterior 0.12, middle 0.5, at anal 
aperture 0.24; diameter of oesophagus, anterior 0.07, middle 0.08, base 0.12; length of oesophagus, 1.25; 
distance to nerve ring 0.57; distance of anal aperture from posterior end 0.45. In this specimen there 
was an intestinal diverticulum, short, bifurcate, prolonged cephalad, and a longer, more slender 
prolongation of the oesophagus. These immature forms a re probably identical with those in the blue- 
fish, squeteague, and others. Figures 117, 118 are sketched from a specimen collected by Mr. R. E. 
Earll, at Charleston, S. C., March, 1880. The capsules were mostly club-shaped, arcuate, or straightish; 
cuticle very finely transverse striate. Length, 22 mm.; diameter, 0.33 mm. 
C'ESTODES. 
5. Rhynchobothrium imparispine Linton. Encysted on viscera. Found in 1899. See 5, pp. 799-801. 
6. Rhynchobothrium speciosum Linton. On viscera. 5, p. 802. 
7. Rhynchobothrium. Encysted on viscera. 5, p. 796, pi. lxiii’, figs. 10-13. 7 , p. 280. Found in 
1899 and 1900 in a large proportion of the scup examined. 
8. Tetrarhynchus bisulcaius Linton. Stomach wall. 5, p. 810. 
9. Larval cestod.es (Scolex polymorphus Dujardin) . Free in intestine. 7 , p. 280. See 4, p. 791. Seen 
frequently in 1899 and 1900. 
TREMATODES. 
10. Distomum vitellosum Linton. [PI. xxx, figs. 333, 334.] See 7 , p. 290, pi. xxxvii, figs. 38, 39. 
Seen often in 1899 and 1900, but always in small numbers. 1 append notes made on a specimen 
taken August 23, 1900. Worm small (1.2 mm. when at rest), very active while in sea water and salt 
solution, neck extremely mobile, stretching to thread-like thinness and contracting until the suckers 
were close together; general outline, proportions, and appearance of the body undergoing constant and 
perplexing changes; acetabulum much larger than oral sucker and kept expanded, i. e., its walls when 
the specimen was viewed from the side forming a semicircle or widely open C. When placed in fresh 
water the worm soon became turgid, with neck reflected, acetabulum contracted until its walls were 
close together, and distinctly pediceled. See under Clupea harengus, Paralichthys dentatus, etc. 
11. Distomum sp. [PI. xxxi, fig. 346.] 
I here place certain small distomes, which appear to be near D. pyriforrrie, if not identical with 
that species, but until more material is available and a careful comparative topographical study of 
these small forms can be made it will be better perhaps to leave them without specific designation for 
the present. These are small, usually oval, flattened, white distomes, with minute spines. They were 
most numerous in small scup, seen frequently (but in small numbers) in this and other hosts. The 
identification of these distomes is difficult, on account of the spines, which apparently fall off easily. 
See No. 21 under Paralichthys dentatus, No. 11 under Rhombus triacanthus, and No. 15 under Pornatomus 
saltatrix. One of these distomes, collected August 29, 1900, was placed under slight pressure and seen 
in favorable conditions. Spherical bodies with concentric structure were present in the excretory 
vessels, and the cirrus was seen to be spinose. A cell from the germ gland was seen entering the shell 
mold. It appeared to be attached by a slender pedicel for a few seconds. It was surrounded by 
