FISH PARASITES COLLECTED AT WOODS HOLE. 



291 



Testes two, rather 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 

 large, 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 acetabuluiu to the right, the cirrus, which is a 

 'conspicuous organ, opening beside the uterus Justin front of the acetabulum ; spines \\eronotedin 

 sections of what in an everted cirrus would bo the somewhat bulbous base; ovary globular, much 

 smaller than testis, approximate to anterior edge of anterior testis and on the right of the median 

 line; the vitellaria consist of numerous small bodies, which lie along the lateral margins and at the 

 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 lie between the anterior testis 

 and acetabulum and contain rather large, riot numerous ova. 



A large number of measurements were made of mounted specimens, and considerable variation 

 was found in the proportions of even such usually constant organs as the 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 O.lti, breadth 

 0.13. (2) Of a mounted specimen, length 1.6; oral sucker, length O.OTti, breadth 0.114; acetabulum, 

 length 0.155, breadth 0.155; pharynx, length 0.08G. breadth 0.070. Longer diameter of ova in sec- 

 tioned specimen 0.055, shorter diameter 0.035; ova in a specimen cleared up in acetic acid measured 

 O.OUO in the longer and 0.035 in the shorter diameter. 



These specimens agree very closely with 1 '> . faxcialunt, Rudolphi, but differ in the ratio of oral sucker 

 to aeetabulum. In D.J'ascialum the acetabulum is double the diameter of the oral sucker; furthermore, 

 the o'sophagiis, i. e., that portion. of the alimentary canal between the pharynx and the intestinal 

 rami, is represented as longer than the pharynx, and the pharynx as following the oral sucker 

 directly. In I>. pudeiix the diameter of the acetabulum, while greater than that of the oral sucker, is not 

 twice as great, and the pharynx is followed by a very short oesophagus, while it is separated from the 

 oral sucker by a distance about equal to its length, except in cases of inversion of anterior end. 



Distomurn vibex sp. uov. 



[Plate 38, figs. 48-51, U. S. N. M. No. 6515.] 



The following description is based on alcoholic specimens collected by Dr. F. P. Gorham, June 11, 

 from the smooth puffer (Sphcroldcs maculatus), pharynx and intestine: Body unarmed, sublanceolate, 

 thick, convex above; neck concave beneath; acetabulum much larger than mouth; aperture trans 

 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; (esophagus short; 

 intestinal rami simple, extending to posterior end of body; excretory vessels largo; testes two, 

 lateral, behind acetabulum and in front of the folds of the uterus; ovary subglobular, in Iron I 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.felHn Olssou, 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. The 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- 



