158 T. B. ROSSETER ON HYMENOLEPIS UPSILON, 



a.re a facsimile of c, Fig. 4, in PfafF and Olrik's collection, with 

 which Krabbe was conversant ; although, like Krabbe, I look 

 upon it as a somewhat doubtful proceeding to judge a species by 

 the hooks alone, yet if the hooks of Pagenstecher's specimen 

 are identical with c and d, Fig. 4, then I am prepared to admit 

 that my specimen and Pagenstecher's are one and the same 

 species. 



According: to Fuhrmann. Cohn studied this worm microsoma 

 and classified it as Dilepis microsoma, but afterwards reclassifi.ed 

 it as Hymenolejns microsoma. In the first instance Cohn was in 

 -error, as both sexual pores are in the same sinus, I am not 

 acquainted with Cohn's work on this species, but I agree that its 

 generic name is Hymfienolepis, in contradistinction to Taenia. 



Although Krabbe says that the egg-mass squeezed out of the 

 last segments of the 40-mm. worm in Pfaff and Olrik's collection 

 was similar to Pagenstecher's, yet we get no information other- 

 wise from Krabbe of these '''' snore-AeggemasseT On comparing 

 the detached proglottides I found amongst the faeces of the 

 -duck, and containing the v-shaped uterus, with the ultimate or 

 twenty-fifth segment of my specimens, I found they had elongated 

 themselves 0"439 mm. and expanded 0'025 mm. in excess. The 

 fact that the intestinal tract of the duck contained no other 

 species of tape-worm was convincing proof to me that these 

 iieparated proglottides were detached portions of the strobila 

 of this worm, and consequently I must give credence for 

 Pagenstecher's being the same. The aggregation or massing of 

 the uterine eggs also occurs, according to Krabbe, in T. circum- 

 ciiicta (Krabbe, No. 21). In the gravid segments of Liga 

 hrasiliensis {vide Kansom's Taenoid Cestodes of North ATiierican 

 Mirds, p. 24, fig. 13) the uterine mass is similar to the v-shaped 

 uterus in my specimen.* But then too much stress must not be 



* Since the above was written I have found amongst the faeces of the 

 lower intestine of a mallard duck a globular sac containing tape-worm 

 embryos in the hexacantb stage of development. It was 0-643 mm. in 

 diameter; it contained from 200 to 250 embryos 0-03 mm. in diameter 

 and embryonic hooks 0*013 mm. in length. The embryos were enclosed 

 in other globular sacs whose contents varied from three to eight in a 

 group. On comparing with the uterine proglottides of Ajyloparahsis 

 (^Taenia) furcifera {rhomhoidea), and seeing that this portion of the 

 duck's intestine was infested with this species, 1 am inclined to think 

 that this is a uterine sac, the product of and expelled from a disintegrated 

 terminal segment of the same (Fig. 9). 



