302 THE ABIERICAN MONTHLY [Sept. 



In the calcedonized flints, there can be observed the 

 peculiar lobulated concretionary strial or parallel wavy 

 bands and capsular bodies. In the flint-likephosphatized 

 pebbles of the Florida phosphate area, we can discern an 

 aggregation of foraminiferal remains, ranging in size to 

 the most minute and in the Jasperized gravels of North 

 Alabama, the polished surfaces permit the sponge spicules 

 and radiolarian like spherules to be readily seen. In 

 the opalized radiolarian clays of Mississippi and Ala- 

 bama, we can also find the evidence of radiolarians, 

 foraminifera and sponge spicules. Polished faces on the 

 silicio-calcareous cement stones of Sendai, Japan; and of 

 Jutland enables various phases of diatom structure to be 

 seen therein. 



In my earlier efforts to obtain some knowledge of rock 

 structure with the aid of the microscope I confined my 

 efforts to the strata of fossiliferous origin, such as the 

 chalks, and crystalline limestones; oolitic strata, and 

 other easily reduced rocks, and during the pursuit of this 

 research, I made unlimited studies from every available 

 source, overlooking the harder series of rocks of igneous 

 and metamorphosed origin, chiefly on account of the ap- 

 parent difficulties to be overcome in their preparation, 

 as for example, the necessity of having diamond treated 

 saws to slit the harder rocks into thinnish plates, and the 

 labor of reducing the slips to the requisite thinness, and 

 giving the required polish to both faces, and for these 

 reasons I gave very little experimental attention to the 

 subject, but contented myself with securing and examin- 

 ing the commercial preparations, the product of the lapi- 

 dary's art; so that nearly every variety of mineral of a 

 fossiliferous nature that came into my possession was 

 subjected to study whenever the simpler expedients were 

 applicable, and matters were allowed to stand at this 

 stage until I worked out the properties of the spherule 



