866 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [148] 



lar in outline. The diameter of the granular or nuclear masses ranges 

 from .02 to .027 mm , that of the entire ovum from .03 to .05 mm . In one 

 case, in a stained segment, there were observed among these granular 

 masses with the transparent envelope a small cluster of amber-colored 

 collapsed shells of ova about .036 and .022 mm in the two diameters. 



The cirrus was invagiuated in every case, but could be plainly seen 

 through the walls of the segment when the latter were rendered trans- 

 parent in glycerine. The retracted cirrus is pyriform in shape, the 

 inner end is the larger, directed anteriorly and a little toward one of the 

 lateral sides. It is very thickly beset with fine bristles. It measured 

 .094 mm in length, and .05 mm in diameter, narrowing to .02 mm near the 

 external aperture. The external opening of the cirrus is near the 

 margin, about the middle of the segment. In the posterior mature seg- 

 ments, which were apparently slightly distorted, the genital aperture 

 was situated from the margin a distance equal to one-fourth the breadth 

 of the segments. 



The ovaries are elongated, glandular, paired organs lying near the 

 posterior end of the segment, one on each side of the median line. The 

 vagina appears to open beside the cirrus on its posterior side. This 

 fact, however, requires further verification. In segments which pre- 

 cede the mature ova bearing segments the retracted cirrus was seen 

 to lie nearly transverse to the axis, inclined a little forward at the inner 

 end, and equal in length to about three-fifths of the segments. 



The testes are represented by a few globular or oval bodies lying 

 along the middle line from the front end of the ovaries to the anterior 

 end of the segment. These range in diameter from .055 mm in some 

 specimens to over .08 mra in others. One of the largest of these oval tes- 

 ticles measured .086 and .047 mm in its two diameters. In those segments 

 in which the testes are best developed the ovaries are scarcely at all de- 

 veloped. Furthermore, the transition from segments with large testi- 

 cles and incipient ovaries, to those in which the interior is completely 

 filled with ova, is quite abrupt. 



The exceeding smallness of this anomalous worm has doubtless caused 

 it to be overlooked heretofore, while the extreme variability of the head 

 might easily lead collectors to regard it as simply fragmental remains 

 of other and larger cestods with which the sting ray abounds. 



