FISH PARASITES COLLECTED AT WOODS HOLE. 
295 
Distomum fragile sp. nov. 
[Plate 30, figs. 68-70, IT. S. N. M. No. 6519.1 
Several small distoma were found in tlie intestines of a sun-fish {Mola viola) on July 18. Ou 
account of their inconspicuous size, and because of the large amount of other material which was 
collected at the same time, tlicso specimens were not given as much attention at the timoof collecting 
as they deserved. Upon going over the preserved material I find that it is not in perfect condition, 
the delicate necks of the specimens having broken in every case. 
The following description is based entirely on preserved material: P>ody unarmed fusiform from 
acetabulum back, depressed ; neck elongated, slender, cylindrical, slightly enlarged at mouth. Acetab- 
ulum a little larger than mouth, subglobular, at base of neck sessile; mouth terminal or nearly so; 
pharynx subglobular, situated a distance equal to twice its length or more behind the posterior edge 
of the oral sucker, followed by a slender oesophagus; intestinal crura simple, beginning in the neck 
about half way between the pharynx and acetabulum, extending to near the posterior end of the 
body; testes two, median, approximate, situated near the posterior end of the body, a little longer 
than broad; ovary subtriangular in outline, lying immediately in front of the anterior testis and a 
little to the right; cirrus and cirrus pouch immediately in front of the acetabulum and to the left; 
vitellaria very abundant, appearing in subangular masses at posterior end and along dorsal and 
lateral regions of the body to and even in front of the acetabulum; uterine folds between acetabulum 
and ovary; ova, relatively large and in moderate number. 
Dimensions of mounted specimen, in millimeters: Length 1.78, diameter of anterior sucker 0.10, 
diameter of neck behind mouth 0.07, diameter at acetabulum 0.24, greatest diameter 0.33, distance of 
acetabulum from anterior end 0.71, diameter of acetabulum 0.14, length of testis 0.17, breadth 0.14, 
diameter of ovary 0.10, longer diameter of ovum 0.060, shorter diameter 0.038, length of pharynx 0.06, 
distance between pharynx and anterior sucker 0.15. 
The excretory vessel was not noted until sections were reached back of the testes, where it 
becomes a somewhat spacious vessel. The posterior seminal receptacle is situated immediately dorsal 
to the ovary. In the sectioned specimen the testes were seen to occupy the whole height of the 
body cavity. In the vicinity of the testes the vitellaria were seen to lie along the lateral margins, on 
the dorsal side nearly to the median lino, and on the ventral not quite so far. Behind the testes they 
extend entirely around the cavity in which lio the two intestinal crura and the centrally placed 
excretory vessel. 
Distomum sp. 
[Plate 30, fig. 71, IT. S. N. M. No. 6520.] 
Brief mention is here made of a distomum, three examples of which were obtained from the sea 
robin ( Prionotus carolinus) August 24. Two specimens of fish were examined. The alimentary canal 
was opened and washed out in water, with the result given above. My notes, made at the time, 
characterize these worms as having the head and prominent acetabulum transparent and colorless, 
the body opaque, white, yellowish behind the acetabulum ; neck very short, arcuate ; body cylindrical 
and slightly irregular. 
Dimensions, in millimeters, of a specimen in sea water: Length 1.06, length of oral sucker 0.07, 
breadth of same 0.11, length of acetabulum 0.18, breadth of same 0.21, diameter of neck at narrowest 
point 0.13, diameter of body 0.26, dorso-ventral diameter of body, including acetabulum, 0.31, same 
behind acetabulum 0.17, same of neck 0.13, length of neck 0.13. The length of another specimen 
was 1.78. In a mounted specimen the pharynx measured 0.09 in length and 0.07 in diameter, and the 
ova 0.048 and 0.031 in the two principal diameters. 
Following are the specific characters, so far as I have been able to make them out: 
Body unarmed, ecaudate, nearly cylindrical; neck short, cylindrical, varying in position from 
arcuate to semierect; acetabulum pedicellate about twice the diameter of the oral sucker; mouth 
terminal; (esophagus none or very short; branches of the intestine simple, extending nearly to the 
posterior end; testes two, median, juxtaposed, dorsal; ovary immediately in front of the testes, 
globular, ventral; vitellaria conspicuous, extending from the posterior extremity to the acetabulum; 
folds of the uterus between the ovary and acetabulum; ova rather large and not very numerous ; 
reproductive aperture immediately in front of the acetabulum. 
These specimens possess many characters common to the forms which I have referred (loubtrully 
to I). simplex Rudolphi. (Trematodo Parasites of Fishes, p. 525). 
