20 Charles GELDERD 



The lower borders are fringed with stiff hairs which takc an oblique 

 direction over thc cminence C. œs. which is the anterior ridge of the œso- 

 phagus seen in latéral section in fig. 3. 



The upper borders of the plates are without the spines that we ob- 

 served in the horizontal figures, for it is to be noticed that thèse spines are 

 only found on the pointed extremities which project furthest into the cavity, 

 cf. FIG. 3. The présent section has been taken just behind the pointed 

 extremities. 



Bands of muscles surround the plates, passing below the ridge c. They 

 are attached to the upper borders, bs, in an oblique direction, consequently 

 in our figure only the transverse sections of thèse muscular bands are 

 seen in inc. 



Fig. 5 has a much différent aspect. 



It has been eut through the plane indicated by the same number 

 in FIG. 3. 



The internai surfaces of the plates is very irregular. 



The upper surfaces are concave, the lower are thickly covered with 

 long hairs which brush against the ridge c which in this région is pointed, 



The lower surfaces of the plates form a pair of deep grooves with c. 



Above the plates a pair of eminences are seen armed with powerful 

 teeth indented on their upper edges like saws. 



The animal possesses two pairs of such teeth. 



Fig. 6 is a section through the plane indicated by the sanie number in 

 FIG. 3 close to the entrance of the pyloric chamber. 



The stomach cavity in this région is much reduced. 



The pièces that it contains are thrown out prominently into the cavity, 

 in close proximity to one another; at the same time the masticating appa- 

 ratus of teeth and spines has become more powerful. 



The upper borders of the plates are armed with a set of small teeth, /. 



We hâve seen the position of thèse teeth in the horizontal section, 

 fig. 11. 



The lower borders are fringed with hairs, which are much less 

 numerous than in 4 and 5. 



The groove formed by the lower borders of the plates with thc ridge 

 c still persists. 



On the dorsal surface of the cavity a remarkable pièce is seen in this 

 région of the stomach, fig. 3, psin. 



