4}^4 Wu. S. 3IARSHALL and X. C. Gilbert, 



Tliis Trematode belongs. we believe, to tlie genus Azygia, 

 agreeing- very closely witli the descriptiou given by Looss (3). Com- 

 paring our specimens with the tigiire Looss (2) gives of A. fereti- 

 coUe and specimens of tliis species wliich we have. we notice several 

 diff'erences between tliem. In A. Joossii. the gonads are all nearer 

 the posterior end of the bodj', their relativ^e positions being, however, 

 very similar. The acetabuliim in A. tereficolle is further forward 

 tlian in A. Joossii, the ovary more in advance of the testis and the 

 excretory bladder narrower and longer. 



Asygia Joossii was found abnndantly in the stomach of the black 

 bass, occnrring bat seldom in the pike or dog-fish. A few examples 

 were found in the mouth and on the gills. It was taken in fish 

 from the three Madison lakes and from Round Lake. While not 

 so abundant as Leitceruthrus the two were generally found in the 

 same fish. 



The oral sucker, 0.425 mm in diameter, is nearly as wide as the 

 body; the mouth is sm aller and leads directly into a well developed 

 Pharynx 0.15 mm in width. The Oesophagus, if present, is very 

 Short and not readily distinguished. the intestinal caeca appearing 

 to arise directly from the pharynx. The long narrow intestinal 

 caeca extend to very near the posterior end of the body, they are 

 much straighter than shown by Looss (2) for A. tereticoJle. 



A Short, narrow duct leads from the terminal excretory pore 

 into the Short, broad bladder which does not extend in front of the 

 posterior testis. In all the specimens of this fluke. when living. 

 the bladder was swollen and distiiictly seen allowing us to separate 

 this from other flukes by the large, bright swelling which appeared 

 in the posterior end of the body. From the anterior raargin of the 

 bladder two long. thin. lateral tubes pass forward into the front 

 region of the body. These we have traced almost to the pharynx. 

 The festes, 0,125 mm in diameter, are situated, one in front of the 

 other. generally, a little diagonally. the posterior being the more 

 constant in its median position. The two festes are separated from 

 each other by a distance not so great as the diameter of either 

 one. The vasa deferentia were seen only for a short distance before 

 they reaclied the cirrus sac. The seminal vesicle is folded and 

 leads into a sliort ductus ejaculatorius which has its opening into 

 the genital sinus just anterior to the opening of the vagina. 



The ovary, slightly larger than either testis. is ovoid, its 

 largest diameter lying at a right angle to the long axis of the fluke. 



