4 THE ROYAL SOCIETY OF CANADA 



cephalus (Rud.) and provided internally with a series of longitudinally 

 arcuate fibres arranged in quite the same way as those actuating the 

 four sets of hooks in the scolex of Triaenophorus nodulosus (Pall.). 

 Furthermore the vitelline follicles are situated in the medullary 

 parenchyma ("Markschicht") as in Ancistrocephalus Montic, 1890, 

 and Anonchocephalus Luehe, 1902. The testes resemble those of 

 Triaenophorus in that they fill up the whole of the medulla. In other 

 respects the genus belongs to the sub-family Dibothriocephalinae 

 Luehe, as mentioned above. The excretory system is, however, 

 considerably specialized since instead of the usual pair of dorsal 

 vessels there is only one, situated in the median line and much larger 

 than the other two placed more ventrally and laterally. In the 

 possession of a second vesicula seminalis within the cirrus-pouch this 

 genus does not differ from many genera of the family Dibothrio- 

 cephalidae in which such an enlargement of the vas deferens appears 

 (Luehe, '99 and '00). 



But perhaps the most interesting feature of this genus is the 

 division into proglottides in the anterior end of the strobila only 

 (apart from the sets of reproductive organs in the unsegmented 

 portion). This is chiefly expressed by and apparently due to the 

 prolongation of the hinder end of the proglottis into four auricular 

 appendages, symetrically situated, which gradually diminish in size 

 until they disappear at about the twenty-fourth joint. Thus they 

 seem to function in relation to the anterior end of the strobila. They 

 are provided with a well-developed musculature which is arranged 

 so that the very border or tip of the structure can very readily be 

 made to come in contact with the substratum. Furthermore, not 

 only the borders of the appendages of the scolex and foremost joints 

 but those of the terminal disc as well are provided with bands of 

 minute hook-like spines, as mentioned above, directed towards the 

 median axis of the strobila, which are surely effective upon the moist 

 mucous lining of the host's intestine. Thus it would seem that the 

 appendages are secondarily specialized in the anterior end of the 

 worm as important accessory organs of attachment, the very simple 

 bothria differing little externally and internally from the foremost 

 proglottides. The rest of the strobila has probably lost its external 

 indications of proglottidation and returned to a primitive condition 

 comparable to that seen in Ligula. 



On the whole the systematic position of Haplobothrium globuli- 

 forme seems to be not only an unique but somewhat isolated one 

 recalling that of the host, Amia calva Linn, which is of great interest 

 to students of ichthyology. 



