FISIT PARASITES COLLECTED AT WOODS HOLE. 295 



Distomum fragile Hp. m>v. 



[ I'l:it<v:!!l, li;s. fiS-70, U. S. N. M. No. fi!>1!).| 



Several Rinn.ll distoma wore found in the intestines of a smi-fiHli (Mnlti mola) on .July 18. On 

 account of their inconspicuous si/o, and because of tho largo amount of other matt-rial \\hirh was 

 collected at thosaino time, these specimens were not given as much attention at the time of collecting 

 as the\ deserved. Kpon going over the preserved material I find that. if. is not in perfect condition, 

 I he delicate necks of the specimens having broken in every case. 



The following description is based entirely on preserved material : I'.ody unarmed fusiform from 

 a.eetalmlnm back, depressed ; neck elongated, slender, cylindrical, slight 1 v enlarged at month. Ace la b- 

 ulnin a little larger than mouth, snbglohnla.r, at base of neck sessile; month terminal or nearly so; 

 pharynx siibglobnlar, situated a distance equal to twice, its length or more behind the posterior edge 

 of the oral sucker, followed by a slender oesophagus ; intestinal crnra simple, beginning in the. neek 

 about half way between the pharynx and acetabnlnm, extending to near the posterior end of the 

 body; test.es 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 

 li I tie to the right; cirrus and cirrus pouch immediately in front of tho acetabnlum and to the. lefl ; 

 vitellaria very abundant, appearing in sub angular masses at posterior end and along dorsal and 

 lateral regions of the body to and oven in front of the, acetabnlum; uterine folds between aeetabulnm 

 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 month 0.07, diameter at acetabulnm 0.24, greatest diameter 0.33, distance of 

 acetabnlum from anterior end 0.71, diameter of acetabulnm 0.11, length of testis 0.17, breadth 0.11, 

 diameter of ovary 0.10, longer diameter of ovum 0.009, shorter diameter 0.038, length of pharynx 0.00, 

 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 tho vitellaria were seen to lie along tho lateral margins, on 

 tho dorsal side nearly to the median line, and on the ventral not quite so far. Behind the testes they 

 extend entirely around the cavity in which lie the two intestinal crnra and the centrally placed 



excretory vessel. 



Distomum sp. 



[Plate 39, fig. 71, TJ. S. N. M. No. 0520.] 



Brief mention is here made of a. distomum, three examples of which were obtained from the sea 

 robin ( I'rioiiotux caroliniis) August 21. Two specimens of fish were examined. Tho 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 acetabnlnm transparent and colorlos, 

 the body opaque, white, yellowish behind tho acetabnlum; ueck 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 paine 0.11, length of acetabnlum 0.18, breadth of same 0.21, diameter of neck at narrowest 

 point 0.13, diameter of body 0.20, dorso-ventral diameter of body, including acetabnlum, 0.31, same 

 behind acetabulum 0.17, same of neck 0.13, length of neck 0.13. Tho 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 tho 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 tho 

 posterior end; testes two, median, juxtaposed, dorsal; ovary immediately in front of the tosfes, 

 globular, ventral; vitellaria conspicuous, extending from the posterior extremity fo the acetabulum; 

 folds of tho uterus between the ovary and acetabulum; ova rather large and not very numerous; 

 reproductive aperture immediately in front of tho acetabnlum. 



These specimens possess many characters common fo tho forms which I have referred doubt fully 

 to />. .<tii)>li:r Kudolphi. (Trematode Parasites of Fishes, p. . r >2M. 



