No. 5.] THE CESTODE MONIEZIA EXPANSA. 243 



for the vas deferens to appear at all when it cannot be formed 

 somewhere near its normal position. The partial furrows end 

 just between the ovaries of a' and b', and accordingly the two are 

 quite closely approximated. This may be another reason why 

 the vas deferens does not appear in a', and it is, I believe, 

 because of this approximation that the oviduct of a' unites with 

 that of b l instead of running independently to the surface. 

 There is a small rudimentary pore on the right edge of a which 

 is wholly unconnected with the ovary a', thus showing again the 

 tendency for the terminal portions of the genital organs to develop 

 separately in the segments of a low degree of individuality. The 

 genital organs, b', appear normal in form and constitution. 

 The vas deferens is present here and in its normal relations. 

 The pores in a and b are somewhat approximated, owing, ap- 

 parently, to the fact that the edge is undivided, though division 

 exists a short distance from it. 



Between c and d at the right there is a distinct, though 

 rather slight, furrow only on the ventral surface, and this furrow 

 becomes somewhat oblique a short distance from the edge, 

 i.e., it extends somewhat anteriorly from the edge toward the 

 middle. Its slight development is not clearly shown in the 

 figure, but it is much less deep than the normal furrow. Dorsally 

 there is no distinct furrow but only a shallow depression extend- 

 ing in the same direction as the furrow on the ventral surface 

 and terminating in the corresponding region (not shown in the 

 figure). As in the case of Fig. 20, / and g, I believe this 

 depression represents what might be called a very rudimentary 

 furrow, and its correspondence in this case with a distinct fur- 

 row on the ventral surface supports this view as regards both 

 this case and Fig. 20. The genital organs, c 1 and d', show pecu- 

 liar relations. There are two complete sets opening by a com- 

 mon pore in d' . In c', however, the vas deferens does not extend 

 to the pore at all, but forms a complex coil just anterior to the 

 ovary and apparently opens directly into the seminal receptacle. 

 A small cirrus appears to be present in the enlarged terminal 

 portion of the male duct which is seen in the figure. This is the 

 only case where such a relation of the male and female organs has 

 been found, unless it occurs on the left side of e, Fig. 22, where 



