PALEONTOLOGY 



FIG. 7 VARIOUS BRACHIOPODS. 



a, a', Obolus appolinis Eichwald, Cambrian, ventral, and dorsal valves : 

 below the umbo in each is the cardinal area (shaded), that of the 

 ventral valve having a median pedicle-groove ; muscle-impressions in 

 outline. (Natural size.) b, b' ', Lingula anatina Bruguiere, Recent, 

 ventral, and dorsal valves: parts as in a, a'. (x^ t .) c, c', Dis- 

 cinisca lamcllosa Broderip, Recent, ventral, and side views. Fora- 

 men black. (Natural size.) d, d' , Dalmanella [Orthis~] elegantula 

 (Dalman), Silurian, ventral, and dorsal valves: muscle-impressions 

 shaded, (xf.) e, e' t Productus semireticulatus (Martin), Lower 

 Carboniferous, dorsal view, and interior of dorsal valve, (x^.) 

 /, g, Umbonal views of ventral valves of f, Schellwienella ; g, Derbya; 

 areas shaded, dental plates (black) showng through the test. A, Urn- 



