CRYSTALLINE STYLE OF LAMELLIBRANCHS 



85 



tive forms, where the style lies in the intestine itself and where 

 there are no typhlosoles, the secretory activity seems to be lo- 

 cated in the two ridges of cells which form a slight constric- 

 tion between the style-bearing and the waste-carrying portions 

 of the intestine. The styles of such species exhibit the same 

 inner core and superficial layers found in the styles of Anodonta, 

 Modiolus, etc. 



Fig. 16 Anodonta grandis; internal surface of stomach wall, dissected from 

 right side, and spread out flat; gs, gastric shield; ig, intestinal groove; int, in- 

 testine; mc, mouth of dorsal caecum shown in fig. 4; oe, oesophagus; r, one of trans- 

 verse ciliated ridges lining the caecum and stomach wall adjacent to it; sis, 

 opening of style sac; t ma, major typhlosole; t mi, minor typhlosole. 



Fig. 17 Lampsilis anodontoides; optical section of crystalline style with 

 attached air bubble, bu, bubble; hy, hyaline layers. 



