BY W. A. HASWELL AND J. P. HILL. 369 



The rostellum (figs. 8 and 9) consists of a stiffish cellular rod 

 enclosed in a sheath and dilated terminally. The substance of 

 the cellular rod, the size of which is subject to considerable varia- 

 tion, consists of vacuolated cells not unlike notochordal cells ; at 

 the anterior extremity is a mass of denser cells. Enclosing the 

 vacuolated cells are two thin layers of muscular fibres, the fibres 

 of the internal layer circularly disposed and those of the external 

 layer longitudinally. Enclosing the rostellum in the retracted 

 condition is a layer of circularly arranged muscular fibres, and 

 outside of all a thin cuticular sheath, from which the rostellum 

 becomes protruded when it is evaginated. 



Below the cuticle in the posterior part of the head and body 

 is a layer of circularly-arranged muscular fibres. The layer 

 of vertically-elongated subcuticular cells characteristic of most 

 Cestodes is not developed. The muscular fibres of the suckers 

 are recognisable though not completely differentiated. 



In some of the specimens the excretory system was to be clearly 

 distinguished. A depression in the middle of the posterior border 

 leading into a small cavity with very definite walls lined by a 

 continuation of the surface cuticle, is probably the external 

 opening of the system, though the vessels were not traced to this 

 point. A circular vessel surrounds the rostellum, and from this 

 are given off four longitudinal vessels with numerous branches. 

 The flame cells are numerous, situated superficially, each termi- 

 nating a minute capillary vessel ; the flames are "0075 mm. in 

 length. 



In his " Menschliche Parasiten,"* Leuckart gives an account of 

 the cystic worm found by Mecznikoff at Odessa in the body-cavity 

 of the common earthworm. The paper f in which this is described, 

 which is in Russian, not being accessible to us, we have had to 

 depend upon the account of it given (with reproduction of some 

 of the figures) by the great German zoologist in the work referred 



* English translation by W. Hoyle, p. 366. 

 t Verhandlungen d. Petersburger Naturf . Versammlung, Zool. pp. 263-266 

 (1868). 



