FISH PARASITES COLLECTED AT WOODS HOLE. 
291 
Tostcs two, ratlier large, median, approximate, anterior testis nearly circular in outline when 
seen from dorsal or ventral surface, the posterior testis a little longer than broad; seminal vesicle 
largo, situated toward the right side at base of cirrus pouch, in which it is partly included, behind 
acetabulum, but passing, with cirrus pouch dorsal, to acetabulum totho right, the cirrus, which is a 
conspicuous organ, opening beside the uterus just in front of the acetabulum; spines were noted in 
sections of what in an everted cirrus would be the somewhat bulbous base; ovary globular, much 
smaller than testis, approximate to anterior edge of anterior testis and on tho right of the median 
line; the vitellaria consist of numerous small bodies, which lie along the lateral margins and at tho 
posterior end ; they extend laterally into the neck as far as pharynx; uterus from genital aperture 
passes back on left side of acetabulum dorsally to folds of uterus, which lio between the anterior testis 
and acetabulum and contain rather large, not numerous ova. 
A large number of measurements were made of mounted specimens, and considerable variation 
was found in the proportions 0 f even such usually constant organs as tho suckers and pharynx. 
Dimensions in millimeters: (1) Of sectioned specimen, length 2.74, greatest breadth 0.57; oral sucker, 
length 0.14, breadth 0.18; acetabulum, length 0.21, breadth 0.21; pharynx, length 0.16, breadth 
0.13. (2) Of a mounted specimen, length 1.6; oral sucker, length 0.076, breadth 0.114; acetabulum, 
length 0.155, breadth 0,155; pharynx, length 0.086, breadth 0.076. Longer diameter of ova in sec- 
tioned specimen 0.055, shorter diameter 0.035; ova in a specimen cleared up in acetic acid measured 
0.069 in tho longer and 0.035 in the shorter diameter. 
These specimens agree very closely with D. fasciatum Iiudolphi, but differ in tho ratio of oral sucker 
to acetabulum. In D. fasciatum the acetabulum is double the diameter of tho oral sucker; furthermore, 
tho (esophagus, i. e., that portion of the alimentary canal between the pharynx and tho intestinal 
rami, is represented as longer than the pharynx, and the pharynx as following tho oral sucker 
directly. In 1). p it den a the diameter of tho acetabulum, while greater than that of tho oral sucker, is not 
twice as great, and the pharynx is followed by a very short (esophagus, while it is separated from the 
oral sucker by a distance about equal to its length, except in cases of inversion of anterior end. 
Distomum vibex sp. nov. 
[Plate 38, figs. 48-51, U. S. N. M. No. 0515.] 
The following description is based on alcoholic specimens collected by Dr. F. P. Gorham, June 14, 
from the smooth puffer (Splieroides maculatus), pharynx and intestine: Body unarmed, sublanceolate, 
thick, convex above; neck concave beneath; acetabulum much larger than mouth; aperture trails 
verse, in most cases retracted, with part of the adjacent body wall drawn into its interior; mouth 
subterminal, aperture circular; pharynx subglobular, contiguous to oral sucker; oesophagus short; 
intestinal rami simple, extending to posterior end of body; excretory vessels large; testes two, 
lateral, behind acetabulum and in front of the folds of the uterus; ovary subglobular, in front of 
testes, dorsal; vitellaria lateral and posterior, extending forward to the acetabulum; genital aperture 
behind the pharynx near the median line. 
This species resembles D.fellis Olsson, but differs especially in the position of genital aperture. 
The specimens vary from 1.25 to over 6 mm. in length. Many of the larger ones are transversely 
wrinkled. Tho smaller ones are smooth, and all present a plump appearance. Many of them had 
become fastened together, probably at the time of immersion in the killing fluid, the acetabulum of 
one adhering so strongly to another as to pull a part of body into a prominent knob. 
The following gives dimensions, in millimeters, of a large and small specimen, alcoholic 
Measurements. 
Large 
specimen. 
Small 
specimen. 
C. 00 
1.34 
Diameter at oral sucker 
1.00 
0.27 
Diameter at acetabulum 
1.80 
0. 00 
Greatest breadth 
2.00 
0. 70 
Breadth of oral sucker 
0. 55 
0. 33 
Length of oral sucker 
0. 53 
0.32 
0. 98 
0 G6 
Length of acetabulum 
0.8!) 
0. 50 
1 iistance between suckers 
1. 00 
0. 55 
Greatest thickness of "body 
2. 00 
0. 01 
0. 059 
0. 029 
