T. B. KOSSETER ON CYSTICERCUS VEXUSTA. 307 



Cysticercus ; and, although I carefully examined the whole of 

 the intestine, I did not find another specimen of this Taenia. I 

 also found in the same localities specimens of the same Taeniae 

 I have mentioned as being parasitic in the other ducks. 



Having related the method pursued in the production, or 

 rather rearing, of this tape- worm from the Cysticercus, I shall 

 proceed to describe them both, prove their identity one with 

 the other, and contrast and show on what points they differ 

 from other species of Taenia, in the category of which they will 

 have to be placed. 



Description of Cysticercus (Fig. 1). 

 The cyst is oval in its formation. Its long diameter is 027 

 mm., its median diameter 024 mm. In the majority of 

 instances of those examined, the embryonic scolex (Fig. la) was 

 well formed. The four suckers (Fig. 1) have the appearance 

 of being strong muscular organs, their length in this the inter- 

 mediate stage is approximately 0'098 mm. long and 0065 mm. 

 wide. The rostrum (Fig. \c) is, like the rostrum of C. gracilis, 

 vermiform or annulated. This vermiform body is, in my 

 opinion, analogous with that which exists in the growth and 

 development of the head of Cysticercus pisiformis, and the same 

 peristaltic action is to be seen in these cystic bodies, even 

 when detached from their nurse. These annulations appear to 

 be strong muscular bands, and are more clearly perceptible 

 when the rostrum is invaginated, or embedded in the soft 

 plasma of the embryonic scolex. The base or crown of the 

 rostrum forms a dome, it then narrows as it descends, and 

 is, as will be seen on reference to Fig. 1, club-shaped in 

 form. Its length is 0144 mm., width at dome 0050 mm., and 

 its narrowest part, that is to say at its termination, 0021 mm. 

 Around the dome of the rostrum are eight well-defined cha- 

 racteristic hooks (Fig. Id), whose length is 0051 mm., and 

 divisible thus : a-6, 0024 mm. ; a-c, 0051 mm.* 



The Tapeworm (Fig. 2a, 26, 2c, 2a*). 



It is not my purpose to give a minute account of this tape- 

 worm, as a special paper will be written describing it in detail, 



* These notes on this Cysticercus were written previous to finding the 

 tape. worm. 



