46 S. GOTO. 



right angles to its limiting membrane, and in some places, the fibres form 

 somewhat strong, compact bundles, which are more deeply stained than 

 the other parts. The outer layer, viz., that in which run the diagonal 

 and the circular muscular fibres, is generally half as thick as the inner 

 layer. It consists of dense, fibrous connective tissue, scantily inter- 

 spersed with nuclei and deeply stained by haematoxylin. This 

 layer is, in most parts of the body, very distinct from the inner layer, 

 from which it seems to be separated by a very thin membrane ; but in 

 some parts, the two layers are not so distinctly separated from each 

 other (PL VIII, fig. 3). 



In Microcotyle reticulata, also, the external portion of the ecto- 

 parenchyma is clearly distinguishable from the inner ; the former con- 

 sisting, in fact, of a dense, diffusely stained, connective tissue, whose 

 fibres run parallel to the investing membrane (PL III, fig. 4). 



In all the other species I have hitherto studied, the ecto- and 

 endoparenchyma are not separated from each other so distinctly as in 

 Axine heterocerca ; but in most species the two portions present 

 different aspects, the ectoparenchyma consisting generally of a dense, 

 fibrous, connective tissue which is niore deeply and more diffusely 

 stained with haematoxylin than the endoparenchyma. There is, 

 however, as above stated, no distinct landmark that separates the two 

 from each other, and even in Axine heterocerca there is no distinct 

 boundary between them towards the two ends of the body. 



The endoparenchyma presents, in most species, different aspects 

 in different parts of tne body. In Axine heterocerca (PL VIII, fig. 1), 

 the endoparenchyma is, in most parts of the body, of a cellular 

 nature. The cells which are of very different sizes in different parts, 

 have usually a distinct membrane and a deeply stained nucleus 

 enclosing mostly a single, but sometimes two or more nucleoli. 

 The cell-body encloses some large vacuoles, and the protoplasm 



