new Genus of Avian Cestodes. 419 



It seems impossible, in face of so many characters which 

 are usually taken to be of systematic value, actually to assij^n 

 this species to Tetrabothrius. But no other genus among the 

 Cyclopliyllidea possesses "auricular aj)pendages/' and this 

 seems to be a feature which n)ay well indicate close affinity 

 between the genera. 



On the other hand, in the possession of a paruterine organ 

 Ociopetalum a))proaches more nearly to the Idiogeninne among 

 the Davaineidie, or to the Paruterininw among the Hymeno- 

 lepididte. Of the former it is worthy of remark that Id'vigenes 

 resembles it in having only one recognizable pair of excietory 

 canals *. But in this subfamily there is an armed rostellum, 

 and nothing in the shape of auricular appendages. The same 

 objections apply to the Paruterininre, except that a few genera 

 [lUiuhdometra, Anonchotwnia, Metroliasthes) are destitute of 

 a ro.-tellum. 



The absence of one pair of excretory vessels appears to be 

 a feature of sporadic occurrence among the Cestodes, and 

 cannot, perhaps, legitimately be taken as of systematic 

 importance. 



It is clear that the auricular appendages, just as much as 

 the paruterine organ, or even both, may have been acquired 

 quite independently of any close phylogenetic relationship, 

 and it is only as a provisional measure that I propose to base 

 the systematic position of the species on the former, and not 

 on the latter. 



Generic Diagnosis. 



OCTOPETALUM, gen. nov. 



[Tetiabothiiidfe?.] Scolex unarmed, without rostellum, 

 but iviih a slight coiiical papilla at the apex. Suckers com- 

 pletely covered by overhanging epaulette-shaped appendages of 

 their anterior borders, each of these appendages having a marked 

 median cleft extending for some distance from its free edge. 

 Neck very short. Segments anteriorly much broader than 

 long. The posterior segments about three times as long as 

 broad, the last being the largest and narrowest. A single 

 pair of lateral excretory vessels present throughout the sti'obila, 

 connected in each segment by a transverse vessel. A single 

 set of reproductive organs in each segment. Genital pores 

 irregularly alternate. Vagina opens behind cirrus-sac, in the 

 same horizontal plane. A paruterine organ developed in 



* Zschokke, " Eechercbes sur la Structure .... des Cestodes," M^m. 

 Inst. Nat. Genevois, torn. xvii. (1889) p. 118. 



