560 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
men the margins in optical section are crenulate and the body tapers , 
towards each end. I can not refer this specimen to any species with. 
any degree of certainty. The former encapsuled specimens are evi- 
dently young forms of those which I have referred provisionally to 
Ascaris tenuissima, although they present some resemblance to Ascaris 
capsularia Rudolphi. 
LEUCISCUS ATRARIUS. 
The nematods secured from this fish were few in number. They were 
found only in the body cavity, where they were coiled up under the ~ 
external tunic of the viscera. They are all apparently larval ascaride, 
although on account of their rudimentary condition I have not been 
able to identify them with certainty. 
One specimen obtained from the serous coat of the intestine of its 
host appeared to be near the stout nematod from S. mykiss mentioned 
above. It was 17 mm. in length. Its greatest breadth was 0.6 mm. 
near the posterior end. Its diameter at the anterior end was 0.25 mm. 
The living worm was for the most part brownish red in color. When 
the alcoholic specimen was examined it was found to be partly envel- 
oped in a thin, transparent, chitinous investment, which, when removed, 
revealed a smooth cuticle, with a broad, prominent lateral line. The 
breadth of the lateral lines was about 0.07 min. at the anterior end, in- 
creasing to 0.1 mm. toward the posterior end. The surface, except along 
the lateral regions, presented a reticulated or squamose appearance. 
When the specimen was placed in glycerin the reticulations were no 
longer visible. Fine transverse fibers and strong longitudinal fibers, 
however, became visible in the cuticle. 
The neck is continuous with the body, the head narrow, truncate, 
mouth terminal, with rudimentary lips. The body is gradually atten- 
uate anteriorly, but tapers abruptly and somewhat unequally on 
opposite sides to the rather blunt posterior end; anal aperture terminal. 
At the posterior end there is a minute, bluntly rounded, papillary 
spine, 0.012 mm. in length. Nothing could be made out with regard to 
the esophagus or genital organs. 
In addition to the above, some small white nematods were obtained 
from the mesentery. These were about 7 mm. long and 0.35 mm. in the 
greatest diameter. The anterior end is nearly truncate and 0.1 mm. in 
diameter. The body tapers nearly uniformly to each extremity, but in 
some more abruptly towards the posterior end. ‘The lateral lines are 
prominent. The surface of the body is smooth, the longitudinal muscles 
well developed, giving a longitudinally striated appearance when 
magnified; transverse strive are not visible in alcoholic specimens, but 
become visible when treated with glycerin. The number of oral lobes 
is not definite, but there are several small oral papille. The genital 
organs are rudimentary, the anal aperture terminal. These specimens 
resemble the larger specimen closely, but in life were white, while the 
