16 DR. F. E. BEDDAED ON 



While there is no need to insist upon the difference between 

 Ichthyotcenia nilotica and any of the other species described in the 

 present communication, it is equally clear that there are consider- 

 able resemblances between that species and /. biroi. They are 

 however, as I think, distinct. In the first place, our knowledge 

 of these pai'asites of Varanus shows so far that, while a particular 

 species of Varanus may harbour more than one species of Ichthyo- 

 tcenia, the same species of Ichthyotcenia does not infest more than 

 one species of Varanus. But thei-e are also definite structural 

 distinguishing marks. Of these the most important is the form 

 of the ovary, which is quite normal in /, nilotica and peculiar in 

 I. biroi. The spiny lining of the cirrus appears to be a further 

 distinguishing mark, as Schwarz in his general account * of the 

 anatomy of the genus says nothing about it. 



An example of Varanus varizis contained specimens of tape- 

 worms which were clearly i-eferable to two species — one very 

 much larger than the other. The smaller species was repi^esented 

 by only one individual, which was a delicate thread-like worm, 

 quite agreeing with Acanthotcenia tidswelli of Johnston t in that 

 '• to the naked eye it appears like a piece of fine white thread.'"' 

 Furthermore, the head is covered with minute densely-set 

 spinelets. In other external characters, however, this small 

 worm does not agree with Acanthotcenia tidswelli. It is very 

 much smaller, not reaching be3^ond 6 mm. in length as compared 

 with 30 mm. for Acanthotcenia ticlsioelli ; there are abundant 

 calcareous bodies, and the segments are rather cleai^ly defined 

 after the neck. The neck is quite short, and the segments soon 

 get to be as long as they are broad. I counted altogether forty 

 distinct segments after the neck. 



Of these the last few had an oval outline and were deeply con- 

 stricted at their junctions. Whether these were fully mature 

 segments or not. I am unable to state, as I could not see the 

 organs of reproduction in the single specimen, which was mounted 

 entire in glycerine; nor, indeed, could I see the generative pores. 

 It is thus only bj^ inference that the Avorm is referred to the 

 genus Ichthyotcenia (from which it is, as I think, very difficult to 

 distinguish Acanthotcenia), with which, however, all available 

 characters agree in uniting it. I should say that, as might be 

 expected, the head is entirely unarmed with hooks ; it is con- 

 siderably wider than the ensuing neck and the body for some 

 distance. Mr. Johnston found the minute spinelets of the scolex 

 in A. tidswelli to occur also upon the following proglottids. I 

 have not been able to ascertain that this is so in my species. 

 On account of the very scanty amount of notes which I am able 

 to set down concerning this species, I do not for the present give 

 it a name. 



The second very much larger species, Avhich I propose to name 



* Loc. cH. p. 1 3. 



t Proc. Roy. Soc. New Soutli Wales, vol. xliii. 1909, p. 103. 



