i- 5 6 



EDWIN LINTON. 



opposite the reproductive apertures. On the opposite margin a 

 vitelline mass separates the two vaginse and, like the testes, belongs 

 to both components of the double segment. 



There is no line of demarcation between the two components. 

 The margins are continuous and smooth everywhere except 

 between the reproductive apertures where the minute serrations, 

 which are characteristic features of younger portions of the 



strobile, are seen. These ser- 

 rations are inclined towards the 

 extremity of the smaller part, 

 and may be taken as belonging 

 to that part. 



There is no indication as to 

 which is the older of the two 

 parts, except a slight difference 

 in size. Evidently the reversal 

 took place very soon after the 

 primary segment was formed. 

 Although the segment was not 

 seen attached to its strobile it 

 is not conceivable that the ab- 



normal condition was assumed 

 after separation from the stro- 

 bile. 



It is to be noted that there 

 is a reversal in a dorso-ventral 

 direction also, the vagina and 

 oviduct lying above the uterus 

 in one part and below the ute- 

 rus in the other. Or, to state 



FIG. 2. After Blanchard. Abnorm- thig compar j son in another Way, 

 ality of genital organs of Tcenia saginata. 

 A, C, normal segment ; B, abnormal 

 segment. 





if the specimen were folded to- 

 gether on a hinge-line crossing 

 transversely between the vaginse 



the two components would not be symmetrical to the plane of 

 their apposed faces, but one would correspond in the position 

 and arrangement of the parts to the other. 



Abnormalities in cestodes are of common occurrence and the 



