AVIAN CESTODES. 867 
medullary parenchyma in the middle of which it lies. But 
although it is definitely marked off, it has not an outer layer of 
circular muscles, such as will be described presently in the 
completely adult paruterine organ. ‘The principal distinction 
which the paruterine organ shows in comparison with the 
Text-figure 4. 
Portion of a transverse section of a young proglottid ot Rhabdometra cylindrica. 
The greater part of the medullary region is occupied by the paruterine organ. 
e Calcareous corpuscles in the paruterine organ. d.v. Dorso-ventral 
muscular fibres. ¢. Transverse muscular fibres. 
surrounding medullary region is the much denser character of the 
parenchyma, which no longer presents the appearance of a delicate 
network with clearer circular or oval interspaces. The network 
is here and there quite visible in parts, the whole tissue being much 
