384 DALE— CAMBRIAN MANGANESE DEPOSITS OF [April 25, 



Fig. 7. Microphotograph of sponge spicules, 219 B6a; slide 257; en- 

 larged 22 diam. a, sponge spicule ; b, hematite ; c, calcite. 



Fig. 8. Microphotograph of limestone, 219 Bsd ; slide 253 ; enlarged 22 

 diam. a, calcite; b, phosphatic? material. 



