2 THE MICROSCOPE. 
his little favorites by the grinding and pulverising effect of the 
ruthless steel. An examination of the mingled mud and sand 
pumped to the surface shows plainly enough this destructive action, 
but strange to say, a large percentage of the diatoms are unbroken 
and enough remain to show this one of the most beautiful and 
characteristic parts of the great Atlantic coast deposit. 
Many varieties of Coscinodiscus appear, among which may be 
particularly mentioned the beautifu] C excavatus of Greville. The 
genus Craspedodiscus is represented by a greater variety in size and 
form, than I have seen elsewhere. T. Marylandica is abundant and 
presents most remarkable variations of form, from a well-defined 
triangle to a nearly perfect disc—with and without central umbili- 
cus. It was perhaps one of these last that was classified as Sym- 
bolphora Trinitatis by Ehrenberg—a puzzle and aggravation to every 
diatomist who has since looked in vain for this wonderful species. 
There are several other lively forms new to me, and not shown by 
Schmidt or Van Heurck. Some day perhaps, our kind editor will 
get up illustrations of these, as a mere verbal description would re- 
veal but little of their beauty. A serious reflection for us Atlantic 
coast dwellers occurs in connection with this discovery—if a de- 
posit which comes to the surface at Richmond, Petersburg and many 
other points about the same distance from the coast in Virginia and 
Maryland, is found buried 300 feet deep just over Chesapeake bay; 
it is evident that matters are not progressing with that steady uni- 
formity so desirable to inhabitants of the surface of our planet and 
that, being, so to speak, perched upon one end of a continental see- 
saw, our posterity may in the course of 15,000 or 20,000 years find 
their local habitations raised toan uncomfortable height or, perhaps, 
buried deep under the waves of old ocean once more. 
Below is a list of the forms identified, many of which although 
clearly of the same species as are found in other parts of our 
diatom formation, are still distinguished by such peculiarities of 
outline or areolation as marks them distinctly for this locality: 
1. Coscinodiscus Oculis Iridis. 
2. “by excentricus. 
z. 2g craspedodiscus. 
4. f excavatus. 
5. $i apiculatus. 
6. e radiatus. 
