Smithsonian Report, 1 91 5.— Walcott. 



Plate 13. 



Cambrian Brachiopoda. 



a=area: c/-=cardinal muscle scar; J'=foramen; J''=cast of forammal tube; /)=central muscle 



scar; ■i=transmedian muscle scar; j=anterior lateral muscle scar; (■s=vascular smus. 



Obolus, Diccllomus, Linguldla, AcroHiele, and other genera are represented from localities in the 



United States, Canada, Sweden, France, and China. 



