SCOLKX OF A CKSTODE. 



81 



Duthiersia the layer which is thrown off most externally by the 

 outermost layer in the bothrial groove is quite different. It is much 

 deeper and greatly stained by I'eagents. It presents (text-iig. 5) 

 the appearance of closely approximated plates, thinner towards 



Text-fignre 5. 



Upper figure a section through a portion of the wall of the bothrial tube of 



Sothriclium (Solenopliorns) megacephala. 



Lower figure a similar section of Duthiersia fimhriata. 



I, membrane immediately lining bothrial groove and secreted bj' (e) epithelial lining ; 

 between the two lies another membrane, shown as a darker line. The difference 

 of the outermost of the two membranes in Duthiersia and Sothridium is 

 clearlj' shown. 



Proc. ZooL. See— 1917, No.YI. . 6 



