220 ON A NEW AVIAN TAPEWORM. 



a number of points which we shall have to consider in fixing the 

 position of this worm. It is true that the tlu-ee genei'a mentioned 

 are separated by somewhat slender characters, which is emphasized 

 by the fact that Choanotcenia infimdihidum has been referred by 

 Fuhrmann to the genus Alonopylidium, and that the same author 

 has left the position of Ghoanotcenia Imvigcda of Rudolphi in 

 doubt. 



All the three genei^a, however, seem to differ from that which 

 forms the subject of the present paper by the strong muscular 

 rostellum and by the relatively small number of the hooks, 

 arranged in a single or a double crown. Moieover, the seg- 

 ments in representations of these genera are figured as con- 

 siderably longer in proportion to their breadth than they are 

 in Otiditcenia. Finally (so far as concei'us the more important 

 point), the uterus appears to be a persistent and continuous sac in 

 Choanotcenia and Anoniotcenia, while the eggs in MonopylidAutn 

 come to be scattered singly through the parenchyma. As I have 

 endeavoured to show on a previous page *, the development of the 

 uterus in Otiditcenia is difl:erent. Nevex-theless, I am disposed to 

 place Otiditcenia more nearly in the neighbourhood of these genera 

 than in that of any others. 



With regard to the Davaineidae the present genus does un- 

 doubtedly show certain points of likeness to the genus Davainea, 

 the definition of which genus is not, however, a matter of great 

 ease. Otiditcenia certainly lacks hooks upon the suckers, the 

 existence of which in Dctvainea forms a part of its generic 

 definition. But it must be remembered that D. lateralis from the 

 mammal Gcdeopithecus has suckers without hooks. The breadth 

 of the rostellum and its numerous hooks is a point of similarity to 

 Davctinea, in which genus the rostellum may be rather rudi- 

 mentary (c/". Zschokkef), The principal reason, however, against 

 assigning this worm from Eupoclotis hori to the genus Davainea 

 is the persistence of the uterus to the stage of the jaerfectly ripe 

 proglottids, whereas in " the genus Dctvainea a definite functional 

 uterus is not developed " (Ransom) J, and there are also paruterine 

 organs. 



The generic § characters of Otiditaenia will be, as I believe, the 

 following : — 



Scolex with v?ide hut rather rudimentary rostellum armed with 

 over a himdred miriute hooks arranged in tivo rows. Suckers 

 waarmed. Neck p)resent^ not long. Proglottids for the most part 

 %mder than long., only as wide or slightly ivicler than long at the end 

 of the body. Genital pores irregidarly alternating. Detached pro- 

 glottids very sioollen, almost spherical. Water vascular vessels two 

 pairs, ve7itrcd mttch the larger, nearly or quite lettered to each other ; 

 transverse trunks also luicle. Genitcd organs not mcdure very early 



* P. 210. 



t Centralbl. f. Bakt. u. Parasit. 1895, p. 634. 



t Bull. U.S. Nat. Mus. no. 69, 1909, p. 14. 



§ I do not feel able to differentiate the specific characters. 



