114 JOURNAL OF THE [October, 



a high chalk bluff on Alabama River, and at numerous points on 

 the bluff fresh water constantly trickles down its face. Wher- 

 ever this is the case there is a streak of living diatoms in con- 

 stant growth on the chalk. The species associated, as shown 

 on the slide, are as follows: Synedra fulgens, Cymbella cytnbifor- 

 mis, Cocconema lanceolatum, Navicula parva, iV. veneta, Gompho- 

 nema capiiatutn, Nitzschia pandurifonnis, Suriella ovata, a Cocco- 

 neis, and two species of Melosira. 



" 2. A slide of silicified coniferous wood, derived from gravel 

 of river drift overlying chalk at Gainesville, Ala. A fine polari- 

 scope object. 



"3. A slide of fossil marine diatoms, completely pyritized^ 

 and which completely dissolve in nitric acid, leavmg no struc- 

 tural traces. These diatoms were derived from a stratum of 

 miocene clay encountered at a depth of 700 feet in the third ar- 

 tesian well, recently finished at Mobile. This find of mine cor- 

 roborates a fact of geological interest, as pyntized diatoms were 

 recently found near the Atlantic seaboard, in artesian borings, 

 at Brentford and Clayton, contiguous to the Delaware River. 

 The diatoms, as mounted, are relucent like gold when examined 

 by surface condensed light, and species of the following genera 

 maybe seen: Coscinodiscus, Actinophticus, Triceratiiim, Pleuro- 

 sigma, Navicula, and Synedra, indicated by outline and surface 

 depressions, as the specific reticulation is masked by the pyri- 

 tous deposit. 



" 4. A slide to place upon record the character of the marine 

 sedimentary silicious deposit from St. Stephens and vicinity, 

 Alabama. This tripoli is one of the strata composing that por- 

 tion of the tertiary formation known as the buhrstone, which 

 traverses the States of South Carolina, Georgia, Alabama, and 

 Mississippi. On this slide may be seen about 175 selected dia- 

 toms, polycistina, and foraminifera, showing their metamor- 

 phosed state by mineral infiltration. 



" 5. A slide showing numerous polycistina from the same 

 sedimentary stratum. On the same slide the crystalline grains 

 show bands of prismatic colors arranged axially. Under polar- 

 ized light the bands of color waves travel from the periphery to 

 the centre, or vice versa, as the polarizer is revolved from right 



