438 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
PROTOZOA. 
8. Sporozoa. [PI. i, figs. 1-3.] July 26 and 27, 1899. 
About half the fish examined on these dates were found by Mr. J. A. Stewartson to be infested 
with a parasite among the muscles of the back and side. These were not examined closely at the time 
of collection, but pieces of muscle with cysts were preserved and subsequently sectioned. They were 
then seen to be sporocysts. On July 9, 1900, a young herring 8 cm. in length was examined. The 
flesh along the back and sides, from head to tail, was filled with small white tumors. While these 
were of various sizes, none were large. Two of the larger cysts measured 1.74 by 1.16 and 1.16 by 
0.58 mm. in the two principal diameters. The sporozoa when placed so that the four polar vesicles 
are uppermost are squarish in outline with rounded corners, and measure about 0.007 mm. in diameter 
(fig. 3) . The polar vesicles are of a faint greenish tint, the remainder of the spore colorless. 
Sections of the infested muscular tissue show that the spores lie in clusters, which are in some 
cases enveloped in a definite connective cyst and in others not. The spores were also seen in great 
numbers lying along the intermuscular connective tissue fascia. One instance was noted in a series 
of cross sections where a cluster of spores had established themselves in the midst of a muscle fiber 
(fig. 2). I am informed by Mr. E. E. Tyzzer, who is studying this and other myxosporidia, that he 
has not found the herring infested with this form, but that about half the young alewives examined 
are infested; further, that the sporocysts are not common in the larger fish, and, moreover, the spores 
are not in such good condition. The vitality of the infested fish must necessarily be much impaired 
by the presence of sporozoa in such great abundance in the tissues, whereby they fall victims to 
their enemies in larger proportional numbers than do their healthy associates. It is for this reason, 
doubtless, that there is a less proportional number of infested individuals among the larger fish than 
among the smaller. 
Clupanodon pseudohispanicus, Spanish Sardine. 
FOOD. 
Two small specimens were examined August 15, 1899. 
copepods. 
TREMATODES. 
The alimentary tract contained numerous 
1. Distornurn appendiculatum Rudolphi. Few. Dimensions of one in glycerine, in millimeters: Length, 
0.86; diameter of oral sucker 0.06, of ventral sucker 0.12. 
Pomolobus mediocris, Hickory Shad. 
FOOD. 
July 28, 1899; 1; stomach empty. August 13, 1900; 1; fish scale and pen of squid in pylorus. 
August 16, 1900; 1; fragments of Crustacea and a small crab in alimentary tract. 
NEMATODES. 
1. Ascaris sp. [PI. v, figs. 41—45.] 
Twenty-eight large and 3 small specimens from stomach, July 28, 1899. Length of a male 30 
mm., of a female 44 mm. ; length of smaller specimens, 10 mm. Four postanal papillae and 28 preanal 
on each side in male; of the preanal the 10 posterior are the smaller, the remaining 18 larger and in sets 
of 2; both kinds are in a single row. These specimens have many points of resemblance to A. clavata. 
CESTODES. 
2. Larval cestodes (Scolex polyrnorphus Dujardin). Free in intestine, July 28, 1899, and Aug. 13, 1900. 
For account of similar forms, see 4, pp. 789-792. 
TREMATODES. 
3. Distomum appendiculatum Rudolphi. Stomach and pylorus. See 7, p. 289, pi. xxxvi, figs. 25, 26. 
July 28, 1899; 33. Aug. 13, 1900; numerous. Aug. 16, 1900; numerous. 
Dimensions in millimeters, life: Length, 2; diameter of oral sucker, 0.09; diameter of acetabulum, 
0.18; ova, 0.024 and 0.012 in the two principal diameters. 
