156 T. B. ROSSETER ON HYMENOLEPIS UPSILON. 



that my specimens were taken from, and like them I drew the 

 inference that they were analogous. I shall again refer to these 

 egg-masses. 



The foregoing table with an epitome of Krabbe's monograph of 

 T. microsoma and a summary of my specimen will enable the 

 reader and student in this branch of helminthology to compare 

 the details of that avian tape-worm with this that is under 

 consideration. As the description given by Krabbe and even 

 by Dujardin of the Schilling-Creplin worm is comparatively of 

 little value beyond the specific character microsoma, a small- 

 bodied tape-worm, the difficulty is rendered greater by its being 

 stated to be inerine. 



In those specimens which Pfaff and Olrik found, and which 

 Krabbe examined, their lengths up to a certain point agree with 

 Creplin's worm, but in Pagenstecher's specimen the length is 

 excessive in comparison. The number of hooks in either instance 

 agrees ; but no length or delineation being given by Krabbe of 

 the hooks in Pagenstecher's specimen, one cannot make any 

 comparison between them. 



Those specimens which Krabbe took from Anas fusca and 

 marila, in the former, like Pagenstecher's, they were 2 mm. long 

 and the genital apertures were unilateral ; but, excepting the 

 male organ, unlike Pagenstecher's the other genital organs were 

 but imperfectl}'^ developed. Numerically the hooks were the 

 same as the above, but a few millimetres larger than the 

 smallest in the Pfaff-Olrik collection. In marila the length 

 of the strobila has increased to 30 mm. with 300 segments, and 

 their terminal segments contain mature eggs ; whilst the hooks 

 of the rostellum (no number is given by Krabbe) are normal 

 with the smallest in the Pfaff collection. Such being the case, 

 I have to consider the specific relationship of my specimen with 

 the above helminthologists' T. microsoma. 



Excepting the hooks, Creplin's specimen being bookless, the 

 length of the strobila and number of segments of Pfaff and 

 Olrik's and Krabbe's larger specimen, as described above, 

 precludes, in consequence of their disparity, any comparison with 

 my specimen. Thus we are left with Pagenstecher's specimen with 

 twenty-one segments, the terminal ones containing unripe ova 

 consequently the preceding segments were hermaphroditically 

 perfect ; and Krabbe's 2-mm. specimens with sixty segments, in 



