436 DR. F. E. BEDDARD ON 



Zschokke* in the course of his description of " Taenia argentina^^ 

 but mistaken by him for a testis, with which identification 

 Monticelli associated himself f. Fuhrmann % recognised the true 

 nature of this body, which was certainly puzzling at a time 

 when the paruterine organ, now known in so many Cestodes^ 

 was hardly or not at all understood. Zschokke has rightly called 

 attention to the mass of calcareous bodies lying behind the 

 anteriorly placed paruterine organ. The first beginnings of this 

 oi-gan are not plain to me, so little difi'erentiated are at fii"st its 

 tissues from that of the medullary parenchyma of which it is a 

 part. But I feel safe in saying that it does not put in an 

 appearance for some time after the uterus has commenced to 

 develop. I mention this matter as being of importance, since in 

 the species Rhahdometra cylindrica the paruterine oi'gan appears 

 before the uterus. There is thus in the present species no 

 obvious connection in development between the two organs. The 

 paruterine organ in a fairly eai'ly stage of development lies, as has 

 been stated, anteriorly in the segment and quite close to the 

 anterior edge of the uterus, which is behind it. This surface of 

 the paruterine oi'gan is capped by a rather dense mass of calcareous 

 bodies. The calcareous bodies are not, however, confined to 

 this region of the paruterine organ, or rather to the outside 

 of it ; they also occur scattered throughout its substance, but 

 not in such great numbers and not, where present, so closely 

 pi-essed together. The general outline of the paruterine 

 organ in these not fully mature segments is shown in horizontal 

 sections to be somewhat conical, but with a rather convex base, 

 the latter being anterioi' in position. 



It is, furthermore, to be noted that the paruterine organ is very 

 closely related to the uterus, which lies behind it. The mass of 

 calcareous bodies and the margin of the mass forming the 

 immature parutei'ine oi'gan are divided by nothing from the 

 uterine cavity. The viterus, that is to say, has no anterior wall 

 save that which is furnished by the paruterine organ. There 

 is thus a distinct relationship between the utervis and the 

 paruterine organ. At this period in its development the 

 paruterine body is solid throughout ; there is no trace of a central 

 cavity. In proglottids at the end of the body, which are rather 

 longer than broad and apparently quite mature, the paruterine 

 body has the appearance which is represented in the accompanying 

 figvire (text-fig. 4). This is a representation of a horizontal 

 section showing the paruterine body rather oblong in form with 

 rounded angles. It is sharply marked oif from the parenchyma 

 of its proglottid laterally. Posteriorly it is not marked ofi" from 

 the cavity of the uterus, that is to say the uterus has no wall of 

 its own dividing it from the paruterine organ. The tAvo structures 

 indeed seem to be mutually difierentiated parts of one structure. 



* Centralb. f. Bakt. u. Parasit. iii. 1888, p. 1. 

 t Nat. Sicil. xii. 1892-3, p. 208. 

 J Eev. Suisse Zool. iv. 1896, p. 122. 



