neio Genus of Avian Cesiodes. 415 



and sonic fragments of anotlier form, whicli could be clearly 

 distinguished by its external appearance, even in a hasty 

 examination. Under a low power of the microscope it 

 was seen to have a very peculiar head, which at first sight 

 suggests the genus Tdrahothrius. I have not felt justified, 

 however, in placing it in that genus, on anatomical grounds, 

 and have been in so much doubt about its systematic position 

 that I have felt obliged to create a new genus for it, and 

 propose to name it 



Octojjetalum gutterce, n. g,, sp. n. 



External Features. 



The length of an entire specimen (in spirit) is about 9 cm., 

 and it contains, roughly, 150 proglottides. 



The maximum width is 2 mm. 



The scolex is very interesting and peculiar ; it presents 

 an arrangement of lappets overhanging the suckers, which 

 is strongly suggestive of affinity with TetrabotJirius. These 

 lappets, of which there is one for each sucker, are somewhat 

 epaulette-shaped, and have their free edges turned outwards 

 at about the level of the hinder border of the suckers. The 

 suckers are completely hidden by the lappets, but can be made 

 out beneath them when the head is cleared with clove-oil or 

 creosote. Up the middle line of each lappet there runs a 

 very marked cleft, so that it is nearly divided into two 

 separate halves. Thus the head, when viewed from the 

 apex, looks much like a flower with eight petals, the small 

 apical papilla forming the centre. 



There is no rostellum, unless it be represented in a rudi- 

 mentary condition by the apical papilla. There are no 

 hooks. 



The suckers are somewhat oval, measuring 0*32 mm. in an 

 antero-posterior direction, and 025 mm. transversely (out- 

 side measurements). It is difficult to understand how the 

 suckers can be used for attachment to the host, unless the 

 overhanging lappets are capable of being turned aside so as 

 to allow them free action. From spirit-specimens it is, of 

 course, impossible to say whether this occurs. 



The width of the neck is 0*55 mm. in a specimen mounted 

 in balsam. It is very short, segmentation beginning almost 

 immediately behind the suckers. The segments at the 

 anterior end are very short (about 002 mm.), increasing 

 steadily in length towards the posterior end. The greatest 



