ON A NEW BEPTILIAN CESTODE. 113 



There is an incomplete account of the genital system and 

 consequently, on the above description, the genus cannot 

 be placed in its true systematic position. Apparently Dr. 

 Linstow was not aware of Prof. Ratz's work. It must be 

 evident from what has been mentioned before, that there 

 are striking similarities in Acanthotaenia shipleyi, Ichthyo- 

 taenia biroi, I. saccifera, and I. tidswelli. The cuticle, 

 scolex, rostellum, arrangement of the segments and the 

 position of the genital openings, all resemble each other so 

 that they all belong to the one generic type, the imperfectly 

 described genitalia of A. shipleyi being somewhat similar 

 to those of the other species mentioned. The actual num- 

 ber of testes is in this case of no value generically, since 

 there is probably an increase in their number as sexual 

 maturity approaches. Hence Acanthotaenia, v. Linstow, 

 must either be regarded as a synonym of Ichthyotaenia, 

 Lonnberg, or be more fully described and then regarded as 

 a genus allied to the latter and belonging to the same 

 family. 



Dr. von Linstow considered his specimen as belonging to 

 the Subfamily Taeniinae. He did not recognise the true 

 yolk glands, but regarded the swollen mass (i.e., recep- 

 taculum seminis, etc.) just behind the ovary as a vitellarium. 

 The figures of his species show it to differ from I. tidswelli 

 in possessing a much larger rostellum ; testes not in two 

 distinct fields ; a crescentif orm cirrus ; vagina opening in 

 front of the cirrus; and genital openings situated in the 

 centre of the proglottis edge. Acanthotaenia (Ichthyo- 

 taenia) shipleyi is thus very near I. biroi, nearer in fact 

 than I. tidswelli. 



In none of the species mentioned, except our own, has it 

 been stated that the spines are present on the cuticle 

 lining the cavity of each sucker. Linstow's figure does 

 not show them. If not specially looked for, they are easily 

 overlooked. 



H— July 7, 1909. 



