480 Wm. S. Marshall and N. C. Gilbert, 



appear separable into a bladder and lateral stems biit all parts are 

 niore bladder-like and either emi)tY or fllled at the same time. When 

 the vesicle is filled it occupies an exceeding-ly large space within 

 the hodj, eacli lateral stem being at least one-third the width of the 

 body often appearing- larg-er than we have figured. 



The genital pore is sitnated just within the anterior edge of 

 the acetabulum. the male opening just anterior to that of the 

 female (Fig. 3). The testes, 0.14 mm X 0,09 mm. are very large, 

 reaching in mature specimens a length eciual to one-fifth the length 

 of the fluke. Seen ventrally. they have an oval outline, are sitnated 

 nearly in the same transverse plane, but one always slightly in 

 advance of the other; proportionally thej' are similar in size, shape 

 and Position as the testes of Disfonium cirrigerum v, Baer. Counting 

 the relative positiou of the testes in thirty specimens. we found that 

 fifteen had the right testis sligthly in advance of the left, the other 

 fifteen showed the left testes a little in front of the right. From 

 the anterior margin of each testis a vas deferens passes forward 

 and towards the center. The two soon unite and the tube thus 

 formed widens twice. each time into a large ovoid swelling, a 

 seminal vesicle (Figs. 1 and 3, vsl. sem). This double seminal 

 vesicle varied greatlj' in size in young and old worms becoming 

 large in mature specimens, especially so when filled with sperms. 

 Both seminal vesicles are near the median line. the anterior one 

 often being partially hidden. in ventral view, by the acetabulum. 



The ovary (Fig. 2), is distinctly tri-lobate; its position is 

 median, or nearly so, and ventral to the anterior part of the testes. 

 These three lobes are of equal or nearly equal size, each 0.035 X 

 0.027 mm; the median may be slightly larger than either lateral 

 lobe. In some specimens one or, may be. two of the lobes are con- 

 cealed by the third making the tri-lobate character evident only 

 after a careful examination. An oviduct passes dorsally. In some 

 specimens traces of a shell-gland were seen but we were unable to 

 find any specimen showing it distinctly enough to describe. The 

 receptaculum seminis is large and lies dorsal to the ovarj'. The 

 yolk glands are situated far forward in the body lying at each side 

 of the praepharynx and pharynx, never extending as far back as 

 the intestinal caeca. Each gland consists of a small number of 

 irregulär lollicles the separate ducts from whicli could not be seen. 

 The yolk-ducts pass backwards from the posterior end of the glands, 

 the two ducts meeting slightly anterior to the receptaculum seminis: 



