62 AVIAN CESTODES, 



the reticulated uterus. They appear very early (as will be men- 

 tioned later), and persist for a considerable time, being found in 

 proglottids with eggs in a faii'ly advanced stage of development; 

 but they are here already degenerating, and, by the time the 

 oncospheres have been produced, no trace of the testes can be 

 seen. In many of the segments one may see the individual testes 

 surrounded by a cavity containing young embryos, this reminding 

 one of what happens in many othei' cestodes, e.g., Afonopylidhim, 

 Dipylidium, etc. The whole arrangement of the testes and of 

 the female glands is very similar to that met with in these two 

 genera, and in Davaiiiea. 



The vas deferens passes forwards along the midline at first as a 

 more or less straight tube, above the testes, vitelline gland, 

 receptaculum seminis, and the ovary. In front of the latter it 

 becomes thr-own into a series of folds and coils, and, in a trans- 

 vei\se section of this part of the segment, the vas is seen as a 

 rounded mass of coiled tubes occupying the central portion of the 

 section. It extends forwards almost to the anterior end of the 

 proglottid where it luther sharjjly turns laterally and backwardly 

 in tlie direction of the genital pore. ^\.t about the p(jint where 

 the excretory vessel of the corresponding side passes veiitrally to 

 it, the cirrus-sac is entei'ed. The walls of the vas defer-ens con- 

 tain longitudinal muscle-fibres. 



The cirrus-sac is an elongate tube of approximately equal 

 diameter, extending from about the region of the excretory vessel 

 to the genital pore in a fairly straight course, the length being 

 from 0-12 to 0-13 mm., and the breadth 0*03 mm. .Sometimes 

 the sac is rather more spindle-shaped. In all cases the inner end 

 is iiarrowed to become continuous with the vas deferens. The 

 nuisculatuie of the wall is rather weak, the circular and longitu- 

 dinal fibres being poorly developed. 



The cirrus, which lies in a considerably coiled fashion within 

 its sac, may be everted to a relatively considerable length, the 

 longest .specimens measured being about 0-13 mm., with a iHame- 

 ter of 0-01 1 mm. It is thus a filiform structure. This organ 

 does not appear to pcjssess any armature. In cases where it was 



