EXPLANATION OF THE PLATES. 
PLATE XXIL 
INFUSORIA. 
The figures on this plate were all drawn by the aid of a camera lucida, by Prof, Bailey of 
West Point, “and to the same scale as was used in the plates of the first part of this sketch. 
That scale is shown in fig. 15, which represents y’/olhs of a millimetre, magnified equally with 
the drawings. In the sketches, a represents the side of the animal usually seen, 6, the other 
side.”t 
Fig. 1. Pyxidicula operculata, fossil from Manchester, Mass.—^fluviatile. 
1. a. Pyxidicula operculata? fossil from Massachusetts. 
2. a, b. Pyxidicula ? Fossil in infusorial stratum at Richmond, Virginia. 
3. Gaillonella moniliformis, recent, marine. 
4. 4 a. Gaillonella aurichalcea, recent, fluviatile, at c is seen a globular joint, 
4. b, Gaillonella aurichalcea ? recent fluviatile. 
*5. Gaillonella distans, recent and fossil, fluviatile. 
*6, a, b. Gaillonella varians, recent and fossil, fluviatile. 
7. a, b. Gaillonella sulcata. Fossil at Richmond, Va., recent, marine at Stonington 
Conn, a jointed cylinder composed of several individuals; b, base of one of the joints. 
8. Gaillonella ?-. Recent, brackish water of Hudson River at West Point. 
9. 10, Actinocyclus, Fossil at Richmond, Va. 
11. a, b. Actinocyclus. a, base; b, side view, showing the alternate elevations and 
depressions which cause the light and dark portions seen on a. Fossil at Richmond. 
12. Coscinodiscus lineatus. Fossil in tertiary infusorial strata of Virginia, at Richmond, 
and on Rappahannock river. 
13. Coscinodiscus patina. With the preceding. 
14. Coscinodiscus radiatus. With the preceding, 
15. Scale representing ■rV‘’oths of <1 millimetre, magnified equally with the sketches. 
*16. a, b. Navicula viridis, recent and fossil, fluviatile, c, c, c, c, the orifices. 
17. a, b. Navicula viridis, copied from Ehrenberg. 
18. Navicula-, marine, at Stonington, Connecticut. 
19. Navicula-, marine, with the preceding. 
20. Navicula-, fluviatile, West Point, &c. 
21. a, b. Navicula striatula, fluviatile, recent and fossil. 
22. Navicula-, fossil at Richmond, Virginia. 
*23, a, b. Navicula-, fluviatile, recent and fossil. 
+ Silliman’s Journal, Vol, 43. 
*The species thus marked are the most common fresh water species that are fossil in the State of New-York. Others 
that accompany them will he describsd in the 3d part of this article on infusoria. Vide p. 237, in the supplement to the 
quaternary. J. W. B. 
