164 s. GOTO. 



piece has been cat nearer the fundus of the sucker. This section 

 shews the thickness of the anterior and posterior walls, as well as their 

 fibrous structure. The prismatic fibres, of which these walls are com- 

 posed, are strongly refractive, and are scarcely colored by haem- 

 atoxylin. They seem, therefore, not to be of the same nature as 

 the muscles of the body ; these being well stained by the same 

 coloring fluid. In fact, they seem to be not contractile but 

 elastic fibres. The supporting rods are all of them hollow, with, 

 the inner surface, however, not quite smooth, but with irregular 

 projections, which sometimes unite with those of the opposite side, 

 and form septa-like partitions (Fig. 3). The paired rods are 

 some\vhat triangular in section, and are imbedded in their respec- 

 tive walls along the margins. The rods of the posterior wall are 

 articulated at their bases each with another piece (pp), which is im- 

 bedded in the substance of the wall, and imparts greater strength to 

 it — a flict well in accordance with the circumstance already mentioned 

 that the main bundle of muscle is attached to this wall. Fig. 5 repre- 

 sents a section made in the direction indicated by xy in Fig. 3, i. e., 

 in an antero-posterior direction. In this section, the direct continuity of 

 the anterior and posterior walls is clearly seen ; the U-shaped median 

 piece has been cut but in part, as also the extremities of the paired 

 pieces at the entrance of the sucker. The median piece exhibits, in 

 the posterior wall, a deep cut, where the main bundle of muscle is 

 attached for controlling the varied movements of the sucker. Beside 

 this bundle, weaker (jnes are attached to the paired pieces. The 

 fibrous substance of the wall is Ijounded by a cuticula both against 

 the external world and the surrounding inesenchyma. The support- 

 ins; rods are v^er\- easily broken into fi-aa'ments when the animal is 

 subjected to too much [,>ressure ; and tliis takes place pretty regularly 

 in the manner represented by Nordmann, who, however, describes the 



