NEW ASEXUAL TAPEWORM. 823 



annexed, that the wider end of the worm is the scolex and that 

 the narrower end is the posterior extremity where the proglottids 

 are being shed. The dilated extremity suggests a scolex not 

 altogether unlike that of the genus Dasyurotcenia, which I have 

 lately described to this Society *, and which is characterised by 

 an unusually swelled scolex. Furthermore, there is a slight 

 diminution in the diameter of the worm towards the narrower 

 end, which again conforms to this view, which, as a matter of fact, 

 I at first held myself. It appears, however, that the reverse in 

 fact is the case, and that the narrower end is the scolex end. 

 The opposite extremity therefore is, as I suppose, to be compared 

 to the persisting bladder of the bladder-worm stage of the 

 Cestode. To the naked eye, and even on examination with a 

 lens, the scolex end presents every appearance of being the proli- 

 ferating end of the body, for the last segments appear to be 

 slightly incurved, as is so commonly the case at that end. It was 

 not until I studied this region by means of a series of horizontal 

 sections that I was able to discover its true relations. And even 

 now certain important details are wanting. 



I could find, indeed, no armed scolex, nor any trace of suckers ; 

 if the worm is a member of the Pseudophyllidia and has there- 

 fore only bothria, these may easily have escaped attention in such 

 sections, which would not be suitable for their display. I cut the 

 sections, in fact, under the impression that I was dealing with the 

 posterior end of the body, and without making a sufficiently ex- 

 haustive survey of the external characters. The main arguments, 

 therefore, which lead me to the conclusion that this is really the 

 scolex end are firstly the mode of imbrication of the proglottids, 

 and secondly the presence of large pigment granules, a condition 

 which would hardly be expected at the posterior end of the body, 

 but which is not uncommon among tapeworms in the scolex. 

 As to the imbrication of the proglottids it seems to me to be 

 necessary to regard a segment which overlaps the next one as 

 being anterior to it in point of origin, and therefore lying to the 

 scolex side of it. Judged by this conclusion, the narrower end of 

 the body of this very remarkable tapeworm is the scolex end. 



There is no evidence that a scolex has been lost. On the 

 contrary, the body ends here in a slight median elevation, which 

 is quite unlike the termination of the body were this the region 

 of the detachment of proglottids. This little elevation, however, 

 bears no particular likeness to a scolex, and there are certainly no 

 suckers or hooks to be seen anywhere. Nor is there any neck, or 

 break of any kind, between this region and the first obvious pro- 

 glottid. In this latter, moreover, the lateral and transverse tubes 

 of the water vascular system are as large as in the more posterior 

 segments, and do not end in a coil such as is so frequent in the 

 anterior part of this system in other worms. It may be, of course, 

 that the scolex is in this genus a transitory afiair, as it has been 



* P.Z.S. 1912, p. 677. 



55* 



