Sand obtained from, an Artesian Well. 331 



times larger than those of the last specimen. It also contains 

 numerous grains of the black, coal-like material found in the 

 other, but in this case they are much larger, and yet reveal no 

 organic structure, as they are opaque. Besides these, in this 

 specimen I found a fragment of a molluscous shell, the genus of 

 which I have been unable to satisfactorily determine, but I 

 should judge it to have been a lamellibranchiate. 



C. "52$ feet." 



This is also a coarse sand, of a darker color than the last, finer 

 in texture, and containing also black grains of organic origin. 

 It also contains several fragments of the shells of mollusca, but 

 no other remains of organized beings that I can detect. 



D. " 71 feet." 



This specimen is by far the most interesting of the series, as 

 it is evident to even the casual observer, unassisted by the 

 microscope, that it is from a sea-bottom, having been formed 

 where the water was in a comparatively quiescent state ; that is to 

 say, the particles of which it is made up are for the most part 

 very fine, having scattered through them fragments of mollusca 

 of several species, but in so fractured a condition that it would 

 be somewhat difficult to determine even the genera. On acting 

 upon a portion of this specimen with hydrogen nitrate, a violent 

 effervescence took place, resulting, of course, from the solution 

 of the molluscous shells present. Heat being now applied, 

 most of the organic matter in the specimen was rendered solu- 

 ble, and washed off with carefully filtered water, which was cm- 

 ployed so that there might be no danger of introducing extra- 

 neous microscopic forms. By stirring up the sediment of mat- 

 ter unaffected by the hydrogen nitrate, after thorough washing, 

 and permitting it to stand for a few seconds, all the coarser par- 

 ticles, consisting for the most part of sand, settled, while the 

 supernatant water was cloudy from suspended particles. This 

 was poured off, permitted to settle, and examined by means of 

 the microscope. Besides fine particles of sand, tberewere found 

 in it, as might have Been supposed, scattered fragments, and in 



