272 



Henry Leslie Osborn. 



I. Habitat. 



The worm was encountered for the first time in this state in 

 1909 when specimens were found enclosed in cysts growing out 

 from the wall of the urinary bladder of the common leopard frog, 

 Rana pipiens. A note on this and a figure is given in the former 

 paper (Osborn, 1912, fig. 1). In May 1911 four specimens of the 

 worm were found, occupying the cavity of the right horn of the 

 urinary bladder of a 58 mm female frog. The worms were large 

 and conspicuous dark objects, distending the thin transparent mem- 

 braneous wall of the bladder. They were very noticible, so much 

 so that it would be impossible for them to escape notice if they 

 are at all frequent, in view of the great numbers of frogs which 

 are used in anatomical work. 



The worm was encountered for the third time in June 1911. 

 The worms in this instance were found in the cavities of cysts 



Fig. A. 



Fig. B. 



Fig. A. Sketch of the coelomic viscera displayed by the removal of ventral 

 wall, showing the pyloric region of the intestine and the three cysts in situ. 



Fig. B. View of the posterior end of the stomach and the adjoining intestine 

 and mesentery showing the cysts in detail. 



located in the vicinity of the pylorus, as shown in text-figures a 

 and b. Three cysts were found, of which the two smaller ones, 

 each containing two worms, were located in the mesentery and the 

 third and largest, which contained five worms, took the form of a 

 large outgrowth of the ventral wall of the small intestine, at a 

 point not far removed from the pylorus. The wall of these cysts 



