No. 5.] THE CESTODE MOXIEZIA EXPANSA. 235 



approximated, this being apparently due to the fact that the 

 division is incomplete and the furrow c does not reach the 

 extreme edge. Comparison of this figure with Fig. 16 is very 

 instructive. The relations of the furrows at the left of Fig. 17 

 are almost the same as at the right of Fig. 16, the chief visible 

 differences being that in Fig. 16 the furrow is shallower, but passes 

 over the edge, while in Fig. 17 it is of normal depth but does 

 not extend to the edge. In both cases the corresponding por- 

 tions of the ventral surfaces are without furrows. As regards 

 the genital organs in the shorter anterior portion b in the two 

 cases, we find in Fig. 16, where the dorsal furrow is shallow, 

 only the inner portion of the vas deferens and the pore appear, 

 the two being entirely unconnected, while in Fig. 17, where the 

 dorsal furrow is deeper and thus more nearly normal, a complete 

 vas deferens is formed connected with its pore. Moreover, in 

 Fig. 1 7 the furrow does not reach the edge, and the pore in it 

 is situated somewhat posteriorly, while in Fig 16, where the 

 furrow passes the edge, the pore is in the middle of the edge 

 of b. In neither case does the region b show any trace of female 

 organs. The conclusions regarding the causes of the conditions 

 in Fig. 1 6 apply with equal force here. To my mind these two 

 cases afford ample basis for the views expressed in this paper, 

 but these are supported and confirmed by a mass of evidence from 

 the other abnormalities discussed here, so that the conclusions 

 reached become not only probable, but, 1 believe, incontestable. 



Figure 18. 



In this case a small partial segment is completely marked off 

 by very slight furrows, and the anterior furrows show a very 

 abrupt bend where the 

 partial segment ends. 

 In the complete seg- 

 ment lying just poste- __jL^i-^^r- - ***-.: -\ 



rior the genital organs r 



are normal, but in the 



small partial segment nothing but two small groups of cells 



appear, and it is impossible to determine just what portion of the 



organs they represent. The pore is entirely absent. 



