30 ART. 8. 1. IKEDA : THREE NEW AND 



the trabecular layer (fig. 32, Lt., and fig. 34), which is probably 

 identical in nature with the layer I have described by the same 

 name from the body-wall of the male of Bonellia miyajimai (p. 7). 

 The layer in question of the pharyngeal wall consists of an ir- 

 regular network of strands, inclosing roundish meshes of various 

 sizes. See ßy. 34, which represents under high magnification a 

 small portion of the layer in section. The said strands are made 

 up of a stainable ground-substance, in which are numerous con- 

 nective-tissue fibers and a sparse number of cells, besides being 

 traversed by some isolated muscle fibers {m.f.). The meshes form 

 in reality a system of irregularly branching and freely anastomos- 

 ing canals, the lacunar sinus (l.s.). The sinus contains numerous 

 amœboid cells (w.c), laden with spherules which are of a yellowish 

 brown color in the fresh state and which stain deeply with hemat- 

 oxylin. The cells are of various sizes, the size apparently depend- 

 ing U2:>on the quantity of the spherules contained in the cell-body. 



The peritoneum investing the external surface of the pha- 

 ryngeal wall requires no special description beyond mentioning 

 the fact that it consists as usual of greatly flattened cells. 



Of the several layers composing the pharyngeal wall, the 

 connective-tissue layer of the mucous membrane and the trabecu- 

 lar layer were not known before from any Thalassema. In Th. 

 neptuni, according to Jameson ('99), both the inner lining 

 epithelium and the peritoneum should directly overlie the. middle 

 layer consisting of circular mnscle fibers alone. In Echiurus 

 unicinctus, I have found that a connective-tissue layer is present 

 beneath the inner lining epithelium, but no trace of a trabecular 

 layer beneath the peritoneum. 



The wall of the œsophagus is structurally nearly similar to 



