290 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
anterior sucker 1, breadth through acetabulum 1.25, breadth at posterior fourth 1 4, distance between 
suckers 1.1, thickness behind acetabulum 1.1, thickness at acetabulum 1.5; (2) from sections, transverse 
diameter of oral sucker 0.68, vertical diameter of same 0.47, transverse diameter of pharynx 0.34, 
vertical diameter of same 0.28, length of same (estimated) 0.28, transverse diameter of acetabulum 
1.03, vertical diameter of same 0.65, greater diameter of ova 0.034 to 0.041, lesser diameter of ova 0. 017, 
transverse diameter of ovary 0.48, vertical diameter of same 0.24, length of same (estimated) 0.30. 
Some of the details of structure are shown in the sketches, ligs. 29-37. 
Distomum vitellosum sp. uov. 
[Plate 37, figs. 38, 39, TJ.S.N.M. No. 0513. ) 
Three small distoma associated with others referred to D. ocreatum Mol in, in the hake (Merluccius 
bilinearis), collected August 29, are here described. They were distinguished from the others at the 
time of collecting by their slender conical necks, very prominent acetabulum, relatively large ova, 
and having the posterior part of the body tilled with subangular vitelline masses. 
The species is probably new. It would seem to be a member of a group of species of which 
D. umb final Stossich, D. obovatum Molin, and 1). mormyri Stossich are representatives. The characters, 
so far as they can be made out from my specimens, are: Body smooth, subcylindrical; neck short, 
slender, conical, very contractile in life, in preserved specimens arched above, concave and hollowed 
out beneath; mouth subterminal, aperture transverse; pharynx, immediately following oral sucker, 
elongated; oesophagus not made out, but either none or very short; branches of intestine simple, not 
spacious, extending to near the posterior end; acetabulum much larger than oral sucker, prominent, 
aperture contracts to small, transverse opening with puckered margins, situated about anterior third 
in preserved specimens. Aperture of reproductive organs in front of acetabulum, on left of median 
line; testes two, moderately large, median, approximate, and situated near posterior end; ovary in 
front of anterior testis and touching it, lying on median lino, but a little toward the right; vitellaria 
consisting of numerous rather large subangular masses, which 1111 the body behind the testes and 
extend along the sides as far forward as the acetabulum; ova not numerous and rather large, lying 
between ovary and acetabulum. 
Dimensions in millimeters: (1) Of a specimen in glycerin, length 1.42, diameter of oral sucker 
0.08, diameter of acetabulum 0.25, longer diameter of ova 0.052, shorter diameter of ova 0.031; (2) of 
a specimen in balsam, length 0.88, diameter of anterior sucker 0.10, diameter of acetabulum 0.17, 
greatest breadth of body 0.25, length of neck 0.22, longer diameter of ova 0.058, shorter diameter of 
ova 0.034. 
Distomum pudens sp. nov. 
[Plate 37, figs. 40-47, TJ. S. N. M. No. 6514.] 
Certain distoma from the common flounder ( Paraliclithys den tat as) collected September 5 were 
thought at lirst to be identical with Distomum sp. from the same host, described on page 296; but when 
examined more closely were found to be different. The alimentary canals of four flounders were 
washed out and, after repeated washing and decanting, a large number of distoma were obtained. 
These are of various shapes and sizes, but appear to belong to the same species. The largest when 
living measured from 2.7 to 3.7 mm. in length, with maximum breadth of about 0.8 mm. One of the 
smaller specimens measured 1.2 mm. in length and 0.42 mm. in breadth. 
The following description is based on preserved material : Body smooth, ovate to linear oblong, 
somewhat depressed; neck variable, conical, tapering to mouth, or often shortened by inversion of 
anterior end ; mouth terminal, unarmed; oral sucker nearly circular in outline in a few cases, but in 
most considerably broader than long; acetabulum nearly circular in outline, i. o., when viewed either 
from the dorsal or ventral side, and considerably larger than the oral sucker, situated not far from 
the anterior fourth ; pharynx pyriform, with the posterior end the larger, proportions not uniform. In 
some cases the length is greater than the breadth, in some it equals the breadth, and in some it is less 
than the breadth ; separated from the oral sucker by a distance equal to a little more than its own 
length and from the intestinal rami by a distance less than half its length. These proportions are 
for a specimen in which the neck is extended. When the anterior end is inverted, or even slightly 
contracted, the pharynx may follow the oral sucker very closely and appear to open directly into the 
intestinal rami. The walls of the intestine are very thin; tho intestinal rami are simple and extend 
to the posterior end of the body. The excretory vessel was seen to be spacious and thin- walled at the 
posterior end, but was not seen in anterior part of the body. It should be noted that the specimens 
had lain overnight in water before they were placed in killing and hardening fluid. 
