456 
BULLETIN of the united states fish commission. 
9. Cysts in liver. [Pl. xxvn, figs. 308, 309.] 
These cysts, collected July 14, 1900, are a deep red brown, almost black by reflected light. They 
are globular, except where they lie so close as to touch each other. When cleared in acetic acid their 
structure is seen to be concentric. A granular nucleus of deeper color than the surrounding parts 
could be made out in each, but could not be identified. In one case two nuclei were seen. Those 
measured varied from 0.21 to 0.81 mm. in diameter, with the- exception of one, a very small cyst, 
which lay touching a larger one and was flattened on the touching side, whose two principal diameters 
were 0.06 and 0.1 mm., respectively. It would appear that the tissues of this fish habitually build 
colloid cysts around foreign particles. A thin outer layer of the cyst is lighter colored than the inner 
part, and is evidently unmodified connective tissue. The smaller cysts have essentially the same 
structure as the larger. They are all confined to the surface of the liver. 
Morone americana ( Roccus ainericanus ) , White Perch. 
FOOD. 
Fish, shrimps, and other crustaceans. 
ACANTHOCEPHALA. 
1. Echinorhynchus agilis Rudolphi. Intestine. 1, pp. 490-492, pl. v, figs. 1-6. 3, pp. 534-536, pl. 
lix, figs. 70-72. 
2. Echinorhynchus thecatus Linton. 3 , pp. 528-529, pl. liv, figs. 12-22. 
TEEMATODES. 
3. Distomum tenue tenuissime Linton. Peritoneum. ♦>, pp. 536-537, pl. n i, ligs. 9-12. 
4. Dislomum areolatum Rudolphi. Intestine. 7 , pp. 279, 293-294, pl, xxxix, figs. 60-63. 
5. Cysts with irernatode ova. Liver, etc. 6 , p. 537. 7 , p. 279. 
Centropristes striatus (, Serranus atrarius ) , Sea Bass, Black Bass. 
FOOD. 
Fish, squid, crabs (Eupagurus, Panopeus, Platyonichus, etc.). 
ACANTHOCEPHALA. 
1. Echinorhynchus serrani. Peritoneum. 3 , pp. 534-535, pl. lix, figs. 73-79. 
2. Echinorhynchus sagittifer Linton. Peritoneum. See 1, pp. 493-496, pl. vi, figs. 1,2. 3 , pp. 535-536, 
pl. lix, fig. 80. July 30, 1889; in cysts on viscera. 
3. Echinorhynchus proteus Westrumb. See I, pp. 496-497, pl. vi, figs. 3-5. 3 , pp. 537-538, pl. lx, 
figs. 85-88. Found among cysts collected in 1884. 
NEMATODES. 
4. Immature nematodes ( Ascaris ). 
Found frequently in the mesentery, often very abundant. General characters are nearly uniform 
diameter, tapering at each end; tail mucronate. Agree with forms found in Pornalovms, Cynoscion, etc. 
Twenty-three bass, examined July 30, 1889, had each a large number of these worms, m most cases 
in a tangled mass on the mesentery and pyloric caeca. Many of these might be referred to the indefinite 
species Ascaris capsularia. 
5. Filana rubra Leidy. [Pl. xv, figs. 188-191.] 
Found under the skin of a bass, Washington, D. C., October, 1891. Collected by Miss Sophia 
Oberheimer. The worm was bright red when alive. Dimensions of alcoholic specimen, in millimeters: 
Length, 125; diameter of head 0.4, 5 mm. from anterior end 0.65; median 0.8, 5 mm. from posterior 
end 0.75, one-half millimeter from posterior end 0.4. 
CESTODES. 
6. Rhynchobothrium, larvae encysted on viscera. 4, p. 793, pl. lxh, fig. 12. 7 , pp. 279-280. Aug. 4, 1900. 
7. Rhynchobothrium imparispine Linton. On viscera. 4 , pp. 799-801, pl. lxiv, figs. 9-12. 
8. Larval ceslodes (Scolex polymorphus Dujardin) . Free in intestine. See 4 , pp. 789-792. Aug. 4, 1900. 
