A. “DR: F. E, BEDDARD ON 
more exactitude to the Plerocercus type, but perhaps on the 
whole is nearer to that type than to the others. The fact is 
that the present form and, for the matter of that, the long known 
Cysticercus fasciolaris necessitate the revision of the nomen- 
clature of the immature Cestodes. I do not, however, propose 
such a step in the absence of full knowledge of the present genus, 
Urocystidium, and therefore adopt temporarily the term Plero- 
cercoid. It is I think generally held that the name Prestocystis 
Text-figure 2. 
Transverse section of larva which is figured entire in text-fig. 1, E. 
A, Cavity surrounded by gland-cells, B. Bladder-cavity. C. Third kind of cavity 
perhaps derivable from A, d. Tubes of water-vascular system. 
should be applied to those “ bladder” worms in which the cavity 
of the bladder is filled up to a greater depth with parenchy- 
matous tissue, thus leaving the central cavity comparatively 
small and surrounded by very thick walls. On the other hand, 
Piestocystis might be converted into the Plerocercus type by the 
complete obliteration of the bladder cavity. An apparently 
intermediate condition is recorded by Max Braun in his account 
of the Cestoidea in Bronn’s ‘ Thierreich,” in which (Cysticercus 
