No. 6.] THE CESTODE MONIEZIA EXPANSA. 277 



the ducts in the other segments of the spiral, is undoubtedly 

 determined by the relations existing here. Probably the 

 small size of the dorsal side of c at the right is the real basis 

 of the difference, for it is largely because of this that the ven- 

 tral side of c is so intimately connected with b at the right. 



The segment g is nearly normal in form in the region of the 

 right ovary, and this lies in its normal position. Nearer the 

 edge, however, the dorsal and ventral sides of the segment do 

 not correspond, the ventral surface bending posteriorly, while 

 the dorsal bends slightly in the opposite direction. The ducts 

 and the pore evidently conform to the relations on the dorsal 

 side, but they lie almost directly over one of the ventral 

 furrows. 



Figure J/. 



This case comprises a number of segments which show an 

 approach to the spiral form but do not quite attain it, since 

 most of the furrows are not complete at the left. The figure 

 is a dorsal view. It can easily be seen from the figure that if 

 the furrows on the two surfaces were continued over the left 

 edge, a spiral segment extending through the whole series 

 would be formed. The manner in which a spiral aris.es is well 

 illustrated by this case. The bending of the furrows near the 

 edge on one surface is all that is necessary. Here the dorsal 

 furrows bend anteriorly, while the ventral furrows remain 

 straight, except between a and b, where there is a slight pos- 

 terior curvature. 



At the right the segments are all normally bounded, and the 

 genital organs of the right side are normal in form and posi- 

 tion. At the left, however, where the relations approach the 

 spiral form, the organs show corresponding abnormal rela- 

 tions. At the left of a the anterior ventral furrow is normal 

 in the ovarian region, but turns posteriorly near the edge, and 

 the dorsal furrows bend anteriorly, so that the dorsal side of 

 the segment appears curved forward at the left end. The ducts 

 and pore show clearly the influence of this form. The course 

 of the ducts toward the edge is oblique, i.e., nearly parallel 

 to the dorsal furrows in this region, and the pore lies nearly 



