1 1 78 BULI^ETIN OF THE BUREAU OF FISHERIES. 



on serial sections show positively that such is not the case, but that the crura 

 are simple tubes. The number of folds, twists, and turns depends upon the 

 degree of contraction and usually appears greatest between the acetabulum and 

 the ovary. 



The excretory system is very characteristic of the genus Azygia. An 

 elongate carrot-shaped collecting reservoir or bladder extends from the 

 excretory pore, which is located at the posterior tip, through the center of the 

 body anteriad to the posterior testis. The wall is heavy and is thrown into 

 folds which appear at intervals projecting slightly into the cavity. From the 

 anterior end of this reservoir two tubes pass off, right and left, which are 

 at the start dorsal to the posterior testis; they soon pass toward the ventral 

 surface, but cross the acetabulum on its dorsal aspect and dorsal to the oral 

 sucker and are reflected posteriad. During their entire course they lie within the 

 intestinal crura and usually ventrad to it. Their heavier walls indicate clearly 

 that these conspicuous tubes are more nearly analogous to the collecting reser- 

 voirs of other flukes than to the delicate excretory vessels which here also are 

 seen connecting with the tubes and the reservoir at various points. 



The three germ glands, the ovary and two testes, lie close together in a longi- 

 tudinal row distant from the anterior end about two-thirds the length of the 

 worm. The ovary is most anterior and smallest of the group. An unusual 

 morphological feature is the inclusion of the shell gland, a small yolk reservoir, 

 the ends of the yolk ducts, and the first coils of the uterus within the same capsule 

 that incloses the gland proper (fig. 6, pi. cxxi). The relation of thd ducts as 

 worked out by reconstruction is represented in figure 5 after the studies of Messrs. 

 Anderson and Boyden. This resembles closely conditions as shown by Looss 

 (1894) for A. tereiicollis, although I do not find that he has noted the massing of 

 organs within a common capsule. The uterus extends forward in numerous short 

 coils which all lie within the intestinal crura until at the acetabulum it merges 

 into a short, heavy- walled metraterm. The latter passes dorsal to the acetabu- 

 lum and ventral to the cirrus pouch into the genital cloaca, with an inconspicu- 

 ous genital pore located just anteriad to the acetabulum. 



The vitelline glands lie along either side of the worm exterior to the intestinal 

 crura. They begin a little behind the level of the acetabulum and extend to a 

 point about halfway from the posterior testis to the end of the body. This 

 constitutes perhaps the most striking morphological difference between this 

 species and Azygia tereticoUis, in which the vitellaria do not pass posteriad of 

 the posterior testis. This conspicuous diff'erence in the extent of the vitellaria 

 enables the student to differentiate the two forms at a glance. 



Attention should be called to the fact that on account of this structural 

 feature a correction must be made in the generic description of Azygia, in which 



